I know this is a tricky problem to solve on optimizing costs and trying to get customers refer your service.
Referral schemes work perfectly where incremental costs of adding additional service is marginal, like the case of DropBox.
When the incremental costs are a significant portion and adding additional service is going to impact your CapEx, you need to identify the portions of the service which can be given away with less cost. So in this example, how about a free last-mile delivery for the next shipment for every friend who refereed your service to their friends? This won't hurt your bottom line a lot but brings up the top line.
Another way is leveraging the social angle associated. When someone is shipping a good internationally, the next thing he want to do is tell people about their sharing. Can you actually integrate social channels to your service, so that they can share it with world easily.

One of the largest frustration/gap I see in today's market is: My online journey and coupon aggregation are two different entities and there is nothing that ties them. I am also from India and I see this as a big gap.
For example, if I am searching for pizzahut menu and if I have selected Veg Corn Pizza or something like that, I need to come to a different service to get related coupons. When I come to coupon aggregation service, it lists all coupons related to pizzahut but not to the specific one which I am currently searching for i.e. Veg Corn Pizza.
I see that will be the upcoming innovation to have a seamless experience for end users to effectively derive value out of coupons.
Connect with me over LinkedIn/Clarity, to have a detailed discussion on this.

One of the easiest way is to reach out to MVP's and get connections from them on who use Microsoft Stack.

http://mvp.microsoft.com/en-US/default.aspx

The first question I would ask is: Is this your passion which you are converting to a business model or are you looking for a profitable business model to enter and develop the passion? [Either way you need a passion]
If the answer is former, then you clearly have the answer. Follow your passion. You might be a small player today but as you deliver great results to your clients on your passionate topic, you will slowly turn the stones and add more people who can broaden your company's offerings.
If the answer is latter, you need to look at the competition and entry barrier in each of the varieties and choose the most profitable and less encroaching ones to start with.
The decision to be B2B or B2C again depends on the choice you make and happy to go over them over a call.

I a admitting that I don't have adequate experience in this field, But I can draw parlances from other fields which are selling products for a similar target audience.

If you start from the consumer purchasing journey, it starts from idea of having such jewelry and then progresses towards an interest to purchase such an item. This interest phase is the one which involves researching about the product online and based on the recommendations converts to desire finally being an action to buy.
Consumers typically pass through idea phase from online portals which exhibit such items. So you need to place relevant ads on the product search words which are related to item you are selling.
Post idea phase, consumer enters interest phase. Here he will try to read about all the information he/she can get on the item. So it would be good if you can answer few of the FAQs related to the product on your site. This will help your site to get the consumers who might turn your customers to your site.
I will leave the rest of the sections and strategies to adapt in those phases, to a call as I need more information on the product to avoid giving a generic answer.

Depending on the sector, there will be free reports available from various consulting companies analyzing the various opportunities.
This is an excellent data which can be actionable as you are basing your projections on the widely acknowledged data by investors and on a good research done by a firm specializing in the industry in which you want to enter.
By making your case based on these reports makes your pitch stronger and you come across as a person who has done your primary research well to your investor.
If you want to check up some specific examples on how to use these, I am glad to go over in detail over a call.

Having been in the position as an advisor, this is what I think an advisor expects:

a. Equity Ownership. This depends upon how much involved an advisor into the start-up.
b. A flat fee and a percentage pie on every transaction the stat-up makes(Not the profit margin)
c. At my early stage, all I want is a testimonial from start-up n how I helped this business. In my early stages of adviosrship, I want good customer testimonials. This is a win-win situation for both of us. I get to learn from him many things which I couldn't have done myself.
d. It is strategic importance to my own idea and I would love this company to scale and raise the funding and in this case I would expect a contract from the company which I helped.

This is always a chicken and egg problem. You wont attract customers if you don't have sellers on your market place and sellers won't join unless they see numbers.
This is how I would approach(I won't call it optimal as there is nothing like optimal here as strategies will change based on time, place and demand dimensions)
1. Start from a locality or a city with sellers who are known to be providing good service to their existing customers. Go and pitch to those customers on how they will benefit on their supply chain if they choose your market place. Now once they are on-board to your platform, go talk to their customers on how you are making their life simple by coming to their platform.
2. Slowly expand to other localities and make sure that you add varieties to your platform in the process. Choose the sellers who will provide a wide range of goods in the process.
3. Expand this at a city and then go for state, country and cross-country level.

As you build up the model, make sure you respect the credit cycle of buyers and delivery cycle for customers.e are nuances you want to take care at each level.Setup a call and we will go over this in detail.

I would use pay-as-you-go model which lets me scale as and when required and pay accordingly.
The traditional problem with Home grown software is you can't accurately predict the growth when you open the floodgates. So choosing a pay-as-you-go model works perfectly here.
The other constraint I see with Open source software is most of the them expect a experienced user and clearly lack an established support system which you can get in a paid software.
I would be more helpful if I understand the details in depth and happy to discuss that over a call.

Budget is important but not a 100% essential ingredient for a startup. You should consider employing some of the lean methodologies if you want to optimize on the budget you have .
Startups which deal with information management typically require intellectual capability more than financial muscle. So you can consider starting an internet related startup.
Similarly selling on-line helps you to minimize the marketing costs as you can reach out to initial critical mass using various social media channels/forums to get going.

I would love to have a call with detailed guidance on each of the sub-questions.