Cost of rusty project or parts car

$500.00 is the max I'd go, and only if I really had a need for it or the parts on it. Years ago I bought a one owner 70 more door Dart with 50k documented miles for $400.00. I used it as a daily driver for a year until the brakes went, then parted it out, sold the /6 and trans for $250.00, and traded the front clip for some bodywork. The '75 I picked up in January was an $800.00 investment, and as soon as I asked if he was ready to sell, the wife said "get rid of it".