With that budget you can order 50GHs from BFL that will arrive to you in June... 2014.
Nowadays nobody is going to sell you ASICs for $3-4K. Maybe in a couple of months, maybe in September... But not now. Guaranteed.
For that budget look for FPGAs, forget about ASIC. Cheapest ASIC at the moment is 10GHs ASICMINER blade, which are been auctioned for aprox. 70BTC ($7.000) each. There is a post on the auction forum, bid to get it if you're really so interested in buying.