I have some doubt that you will be able to get the supply you request. I have been in contact with almost every single online computer retailer since before Christmas. Demand is high/supply is low... everything was on backorder I had to prepay for 4-280xs. 2 came in 1.5 months and the other in 2 months. Luckily I did because now prices are 25% higher. Not counting you out but it's hard to see how you will convince wholesalers to do business with you over the likes or NCIX and Tigerdirect. Unless of course demand deminishes.
Nonetheless I wish you luck... I will support the coin by mining, I am still weiry about IPOs. Hope your plan works out for a discount GPU source, the market is competitive good luck