If you can do your own work and are confident in your ability to identify problems before you buy it go for it!
I bought my 97 Geo Metro for $600. 22000 miles later here I have invested an additional $180 dollars into it(including everything except: gas, registration and insurance). Like seriously that's 3.5 cents per mile, and 51 mpg average to boot!
It's worth noting I had to push it 0.8 miles and rip into it in a parking lot with 15°F and snow last month to retime it and replace the timing belt after it broke. Between a tow and shop labor that $10.22 repair could've easily been over $200. Only makes financial sense to buy a old car if your willing to do your own work.