The biggest mistake I ever made was selling mine when I had a short term money crunch. It is still on the road with almost 200k miles on it. I loved it more than my 97 M3 and my 01 330i. It truly was a modern 2002tii. Good luck in your search. Make sure the water pump has been replaced, and the throttle gasket recall service was done. The only gripe I had with the car was the silly infrared control for the radio volume. It is a perfect example of BMW fascination with silly electronic gimmicks that do not improve performance.
There were limited options on the 318is. The options were: cloth seats, sunroof, limited slip differential, fog lights. That's it. Yes there was a 91 318 in addtion to the 318is. I think the ic was also offered, but not sure. What made the is special was the suspension; it was the M-Technic suspension from the E 30 M3. If my memory is correct, the brakes and wheels were larger, but it's been 9 years since I sold mine, and my memory may be wrong about the brakes and wheels. Still my favorite BMW since the 2002tii. I liked it more than my 97 M3 and 01 330i.
It did have M-Tech springs, but not M3 springs. The brakes were 325i issue, a big step up from the M10 powered 318i of 84-86, which had non-ventilated brakes in front and drums in the rear. (I upgraded my 84 318i to 325e brakes all around) 318i was a four door and was bottom basement with no frills. Although it also had the M42 motor and the 325i brakes. 318ic was made and is a great value today. There was no power top, so that is one less headache and it had vinyl, so the seats are usually in good shape compared to E30 325ic cars with leather.
I just bought mine for $4,000. I'm very happy with it for the price. Good body; just a small patch of rust under the rear bumper and 3-4 minor dings. It's a no sun-roof car; red with black interior; working A/C. Not "pristine", but a nice, driveable car for under $5K.
Congrats on the new purchase! Sounds like a great car. Put some elbow grease into it and it will really shine. The seats come out with just four bolts and you can really clean the carpet then. You might even want to rent a carpet cleaner and really go at it. Don't forget to change all the fluids if you have no records of when they were done. These are great cars and if you are a little mechanically minded you can do most of the work yourself. Buy the Bentley manual it will really help when working on the car, or just to understand how to take car of it.