If you're buying off
ebay you have to rely almost soley on the photos supplied, which wont tell you much.
If i were buying one locally i'd want to look at the chainset and cassette particually for wear. If they're worn, you face some reasonable expense sooner rather than later.
If i were to buy off ebay, i'd ask the seller some detailed questions...
What size wheels ? Older racers can have 27 inch wheels, the newer 700's are easier to replace.
Is there any corrosion on the frame, particually near or on the lugs/bosses.
Are the wheels true.
Do the gears work correctly and smoothly.
I'd try to get detailed photos of the chainset and cassette...look for sharks teeth that'd indicate wear. To be fair, older racers tend to be 5,6 or 7 speed...whose geartrains tend to go on forever.
Is the seatpost free ?...if its siezed, you may have a world of pain just getting the seat adjusted so you can ride it.
And so on....but i'd work on the principle if you asked those questions then got a bummer, you'd have a good case with ebay.
If you're lucky admarlow, you can pick up a good stong machine for £80.
Have you tried Friday Ads in your area ?
Open the link, refine it to your town then look in the bicycles section
http://www.friday-ad.co.uk/?gclid=CLKYlcCiiaACFR-Y2Aod0Dt5mA
Ive seen some good bikes locally to me once in a while...no reason it shouldnt be the same in your area.