I found a 1994 ford escort 4cyl,5sp,a/c,p/s,p/b. It has 141000 miles on it and the price $1900. Is this a good buy? :)

Well that all depends on body damage, accidents/repairs, rust, and a whole mess of other factors. To answer the question though, if you can't find anything else wrong with it, it probably isn't too bad of a price. The car should do great on gas.
Find out when the clutch was replaced (if ever), when the brakes were replaced, how good the tires are, etc.
You won't want to dump a bunch of money into the car after paying $1900 for it.

Moose is right. It's value depends mainly on what condition it is in. At $1950 you don't want to put any money into it. Here's the Kelly blue book value for a 94 4 dr. sedan in zip code 16630 sold by a private party.

Good condition--Car is free of any major defects. The paint, body and interior have only minor blemishes and there are no major mechanical problems. Everything should work and there should be little or no rust. The tires match and have substantial tread wear left. $1210

Excellent condition--Car looks new. Excellent mechanical condition and needs no reconditioning to sell. The vehicle has never had any paint or body work and is free of rust. The vehicle will pass a smog and safety inspection. The engine compartment is clean with no visible fluid leaks and is free of any wear or visable defects. Only 5% of used cars fall into this cataegory. $1460

If the vehicle is being sold by a dealer expect to pay $500 more than the private party values. If it is in good condition you should be paying about $1710 from a dealer. You are in the ball park as far as price, but as Moose says you don't want to put any more money into this car.

In Toronto
Beginning of Dec I bought a 97 wagon from a dealer for $2500. Auto,a/c,locks,windows,mirrors,nice stereo,Middle aged woman bought it new,dealer serviced every 3,000 mi,traded in back to the dealer. She did Recent: tires,springs,rad,w.p,t.belt,brakes(4 whl disc),trans service,130,000. Cert,emmision,they did the plates,transfer etc. This was/is a new car,looks like it(underneath too)/runs like it. 3 months I have put 6,000 on it on OFTEN..GRRRrrrr..bad winter roads.
I am EXTREMELY HAPPY!! Fold the back seats down throw my skis,gear in the back.
I drive it about 200 miles a day..about 3 days a week back and forth skiing. Costs about $21-$24 at about .95 to $1.10 per litre for gas That's about 19 to 22 litres..4 1/2 to 5 gallons. It has not taken 23 L for the trip ever. About 42 mpg or so. Driving it about 55-65 mph.

HAS A GREAT HEATER!!!!! WOO HOOO!!!!
Clear windows,drive with a light sweater on,don't even have the heater or fan on all the time..temps about -10/15 C.

Hope it turns out to be as good as my last Escort!