This red Saab 900 S caught my attention, a little more than 130K on the clock, for only £750. It looks like its in pretty damn-good shape, and given how reliable (in general) that they are, that screams "good deal" to me. A shame the gas mileage won't be HUGE (it'd do what, maybe 25 MPG US? So, 30 MPG UK?), but I'll be damned if it isn't a good stripped down and otherwise "normal" car.
That does look like a nice car, and they're so damn cheap too. We've had a couple of the older 9-3s in the family (same shape as that 900) and one of the new ones. Economy isn't much more than 30mpg UK as you said, though it does improve on motorways. However, we've had a number of reliability issues with them, so the older 900 was down on my list as it's a bit more characterful but also being an oldie it doesn't need expensive dealer servicing if it goes wrong!
This has got to be a good one. A Honda Civic Del Sol
Now you're talking - perseverance pays off! I almost included the Del Sol in my shortlist, I've been a fan of them since the original Gran Turismo when one was used in a licence test! I like the shape of them and they're supposed to be much better built than the Civics of the same period.
Also, they come within my budget! Well, the ESi models do. Ideally, if I got any Honda, I'd want one of the twin cam VTEC models (it'd be a shame to get a Honda and then not get one of the proper VTEC ones) and it's very rarely that the VTi models come in under budget. There are plenty of ESi models (single cam VTEC with 123bhp) so the only issue really is that it'd be more of a poseurs machine than a genuinely quick car.
Though @YSSMAN, even the ESi would be quicker than my current car, we're still talking 9 seconds ish to 60 versus 14 seconds for my Fiesta!
The Del Sol is probably more usable than something like the MX5 too, as the boot is pretty big as long as you don't choose the electric roof version.
If I found a VTi in my price range in good condition, I'd bite the seller's arm off.