I doubt with 2500$ to spend you could bitcoin mine and make a living. Your better bet is LTC mining as with a 4Mh/s rate you can make around $1000 per month. You are not going to get rich unless you lay out some major money upfront.
It would be better to take that money and buy bitcoins and play the market.
Also electricity has to be cheap to really reap any gains. I pay $0.0823 kWh which isnt bad ... about $150 to run 4 rigs currently.
https://en.bitcoin.it/wiki/Mining_hardware_comparison -- GPU Comparison for you.
http://allchains.info/calc.html -- Pretty Good calculator.
If you decide to mine for some Litecoins LTC or FTC Feathercoins (the easiest two coins on the market) check out
Litebonk.com or
FCPool.com - 0% fees and quick payouts.
Good luck.