If you have the space for storage and the patience I would recommend purchasing a complete F-body car. Depending on your build objectives you can use many more pieces from the complete car. Much of what you don't use can be sold to recoup quite a bit of your cash outlay.
In my case I acquired a '99 unmolested <48,000 mile Camaro SS for $4500. It was a salvage title car, due to frame damage, that I located through the salvage portion of eBay. It was provided by a couple shady used car salesmen in Maryland. After approximately $100 in fuel I had a total of $4600 wrapped up in the car. For my project I am using obviously the LS1 & T56 but also the electric fans, cruise control, power steering pump and fluid cooler, A/C compressor and plastic fuel tank. I fully expect to sell enough of the remaining items to make this a net zero activity. It takes a LOT of work to completely part a car though.
Best of luck in your hunt.