I posted on craigslist, and got 2 replies - one selling rollers (which I am NOT ready for!), and one selling a trainer he bought in the '70s. That sounded risky to me :-).

Anyway I ended up going for the $89 trainer from Performance (Ascent Mag-3L), and it seems perfectly sturdy. It even has 3 resistance levels. My boyfriend was so impressed (. . . after he put it together for me ) that he went and got one for himself. They had all the trainers set up in the store and he asked, what is the difference between the $89 model and the $269 model? The bike shop guy basically said that low-end trainers have gotten so much better in recent years that the difference is on the margins - the high-end one will be quieter, perhaps a big more stable - but the cheap ones are just fine for most. (This is an uncharacteristic admission for someone who works at Performance!)

I hope he's right!