You should be able to get a 2-stage, 5hp, 50 gallon compressor for way less than $500. Here is nice unit from Harbor Freight
HF compressor
In general, you need compression stages for pressure and HP for volume. Single stage compressors can RELIABLY only go to 70 or 80psig. I know ads say they will do 115psig but that is really tough on them. As compression ratio increases on a stage, the temperature goes up. Two stage compressores split the compression into much milder increases with cooling between the cylinders and everythhing lasts longer. Two stage compressors take the pressure up to +120psig which is what you need for most serious applications. You need 5hp to get in the 10cfm @ 100psi range which, again, most serious tools need.