I'm no trackie but I'm looking to get into it. Based on other people's advice here and elsewhere I got a CycleOps 300 Pro, basically a stationary bike with a massive flywheel (22 kg), powermeter (PowerTap is inside the flywheel). It weighs a lot (I learned after the fact that it's 135 lbs at least, some places say 140 lbs but that may be shipping weight). I almost hurt myself bringing the gizmo up and down stairs to get it into my basement.
There is a 400 Pro version - that has a controllable resistance unit so it acts as a smart trainer, before the term was coined? I couldn't find one locally so I got the plentiful 300. The seller I bought from had maybe 10 sitting around in view and said he had 30 available.
I haven't done much other than set it up right now. However, for me, it has some interesting features:
1. It has an Ant+ computer so it broadcasts to Zwift. Based on that it'll automatically sync with Strava (and save my data on the cloud somewhere). I use Golden Cheetah for my SRM so I can open files in that and have one place to look at power data.
2. It has a PowerTap so it should be relatively accurate.
3. Apparently it can mimic standing start efforts. (*Note below)
4. Around here they're about $500 used, $400 seems low, $700 high. I paid $500.
5. It'll take regular pedals and saddle. Bar is not optimal and not replaceable (at this point).
* Note: literally the first thing I tried when I had it all set up was a standing start. Problem is that on track you want to put your weight over your front axle. On the CycleOps 300 the "front axle" is in front of the front legs, meaning if you lean forward enough you'll flip the entire 300 onto the bars. I almost did that, momentarily picturing a 135 lbs trainer landing on my butt as the rear feet went up into the air. Luckily I managed to recover and the rear feet landed on the floor with a large bang. I haven't tried any efforts since; I'll hack something together to prevent that forward flip.
For me, since I'm short, I need the bars lower (may contribute to the flipping forward). I cut down the head tube a bit, which went surprisingly well. I have to put on a saddle and I'm going to look into hacking the bars so I can put a regular stem/bars on, but I'll use as is as soon as I get the anti-flip thing squared away.
Trainer, at the trade show when they were introduced:
CycleOps 400 Pro - a "smart trainer" version. If on Zwift this would be a controllable trainer. 2009 Interbike, picture I took.
CycleOps 300 Pro - "dumb" trainer version. This is mine, modified with lower head tube. Not yet complete - need saddle, anti-tip thing (maybe long bars attached lengthwise to the feet?).