I've got a set of relatively innexpensive Minoura rollers. They have a mag unit which can be easily taken on and off (I don't use it for warm up) and the resistance can be adjusted. I like it well enough. its not the greatest thing, but its a set of rollers. Just get an inexpensive set and ride the heck out of them. I still use mine in a doorway (probably don't "need" to, but I like the security), by spring you will be riding with much more stability with a much smoother pedal stroke.