Start off small if you can. Consider even working exclusively with Amazon.com at first and add other merchants as the business proves itself. Look at the shop I set up for a pal of mine:
http://www.liptunesmusic.com/cgi-bin/shop.cgi
All the data in the store is coming off of an XML feed Amazon has provided to affiliates. Raw data! People can surf Amazon directly from your website. Set up an interface that exploits it a little better... (allows quick entry of ISBN or whatever), and you're doing really well. Dealing with only ONE affiliate like Amazon might be all you really need anyway (they've certainly got enough products).
Here's the script already done (in perl):
http://www.absolutefreebies.com/dire...ucts-feed.html
I'm a php-head, so I would just translate that into PHP, and connect it with a MySQL backend membership script (for member preferences, etc). Promote it right, and you can work up the business plan for investors as you go. You could be the super-affiliate that shares profits with shoppers 50/50.
Compare the CashCart.com customer to the non-CashCart.com customer, and one will leave the store everytime with guaranteed money coming back to them. I'd certainly shop through you.
I'd give you about 1.5-2 mo. of development for version 1.
The marketeer in me feels bustling with
all sorts of outrageous claims...

- "Make money while you shop!"
- "Discounts never got much deeper than this!"
- "Get rebates on EVERYTHING!"
- "Shopping online has never been smarter!"
If you can aggregate other stores as well, you become a hub that serves the interests of the affiliate programs you're using even more.
~ Nexus