Your groupbuy says
About to start new mining rig, but greedy as f*ck in terms of hardware? I may have solution for You! Atm I have access to 27x SAPPHIRE R9 280X TOXIC OC 3GB DDR5 384-bit cards.
But In reality you just want to collect btc and buy all cards and sell them, but I doubt anyone is going to handover their bitcoins to a new user with no trade history.
You should try to get loan locally from someone and buy all cards then sell them here or try to get loan on btcjam or just take PAYPAL Loan to buy your 4 cards.
Ps: I'm wondering how will you convert btc to fiat and at what rate? Does your supplier accept BTC?