Run a search through on www.autotrader.com or www.cars.com

Both of these sites should give you some nice results.

If at all possible... its definatelly try and find a car with less than 100K miles.
Also if all you are looking for is reliability and gas mileage... go with a Civic LX or DX.... as they have less powerful engines and are cheaper than the EX. You can find a cd player to put in for 100$ so I wouldnt worry about the EX goodies that come with it. Also... don't limit yourself to the civic... with the two sites you can just put in the specs you want and it finds it for you. You may also want to consider a 94 - 96 Acura Integra LS or GS, or a 96+ Nissan Sentra. Don't keep Honda Accords out of the question... I helped a friend find a 2000 accord with less than 50K miles on it for 7.5K.... you can find a 95 with < 100K mi. for less than 4500.

Just search those sites and check back a few times a week as new listings are always popping up.