Anyone know much about them?

I'm planning on getting one to ride to work on occasion and go on some rides with friends. I keep checking locally for a nice second hand one as they come up often, but now I want one, they're not popping up!

I don't really know too much about them but I want to spend around £100-£200 and get the best possible, used or new doesn't matter.

Or at least gives me some advise for when I'm looking (complete fish)
I've been told so far that I want Disc Brakes & Front Suspension (full isn't needed) and that GT are a good make to buy. That's my total knowledge, feed me more! :f_biggrin:

Just over budget but what about this one?
But is collection only >.<

Any other Brands I should look for/avoid?