You'd be better off putting some time into Freelancer.com and investing that money into a couple of decent GPUs.
By chance, have you had a chance to look at the current hashing level? If not, pleast take a look.
Do you happen to notice something over on the right side?
That is telling us that a lot of mining capacity is getting powered down.
Allow me to share a little secret with you. Those aren't FPGAs (e.g., BFL singles) shutting down -- because the bitcoins earned by those is still greater than the cost of electricity. Those that are dropping out are those mining with GPUs. The current profitability chart shows that anyone mining on GPU and paying about $0.10 per kWh or more is losing money with every hash. (i.e., you are paying over spot rate for those coins.)
This is the result of the halving of the mining block reward subsidy that occurred at the end of November.
As soon as the first ASICs from the multiple manufacturer currently racing to be the first start going online, then not even $0.10 per kWh will help the GPU miner, even one with "a couple of decent GPUs".