Honestly, if you're not going to be using a training app such as Zwift, Sufferfest, TrainerRoad, etc... I'd just go with your first thought and get a decent fluid trainer. I'd strongly recommend shopping Craigslist. I found a very lightly used Elite fluid trainer that currently retails for over $250 for $70 locally on CL.

Personally, I generally ride rollers and watch Netflix when I'm indoors [I do record with Zwift as it's a good approximation of milage]. I have a cheap $160 set of rollers from Performance that I added resistance to with magnets. I like rollers better as I honestly can't stand not being able to move around a bit when I ride or have the bike completely fixed when out of the saddle.