They can be picked up new for about £100, so they're certainly cheap. A lot of reviews say the Behringer bass stuff is poor quality. Whether that's the case or not, I'm not sure. I looked at this head myself a while back, but opted out for an alternative for a bit more money. Now I'm considering the 90Watt combo version to use in college. The combo is roughly the same price too, depends what you'd rather have.
I know a guy with a Behringer full stack, one of those discontinued powerpack things (which you can still buy all the parts separately for about £300-£500). I'd recommend trying one of these before you buy, and if the reviews are true, and you do buy then get a long enough warranty
But to be honest, there's definitely better stuff if you buy used. That's what I was told, and it turned out all true for me. Got a full stack for £340, and it's good stuff too, in my opinion.
Anthony.