I have 2 Kurt Kinetic Road machines... got one, liked it so much that I got a second one when my husband started riding. They're about $400, but money well spent, I think. When I was shopping for that second trainer, I looked into the cheaper end of things, and didn't like what I found... some trainers were noisy, and most had a quick spin-down time, which made pedalling smooth circles very tough, and I really didn't like that jerky motion, bad enough that it might put me off using the trainer.
So, try before you buy... not all trainers are created equal, and it's worth spending a little more sometimes, especially on something important like fitness. Would someone else be willing to go in on the gift with your mom?