Worth doing? Talking bikes and frames here rather than anything else.

Any pitfalls to avoid?

If they have spelt anything wrong in the advert, run away.

Countless pitfalls, first rule is check it as thorouglhy as you can once it arrives and use feebay if possible or go view it, that way you can make a claim if you have to or walk away.

Is it a full sus or hardtail bike?

Full sus

collect only and caveat emptor.

As long as you don't pay over the odds 2nd hand frames are well worth a punt in my experience, shocks and bearings can be fixed.

had some bad experiences with ebay bikes/frames but buy off here and have a chat with the seller first. You can get a good impression of how genuine they are fairly quick. Worth checking their post history too, make sure they are genuine site users.
I bought a gem of a bike off here not long ago, well chuffed! and i have just bought a frame off someone else today, not got it yet though, obviously

A lot of my kit is second hand, all my forks have been other than the rigids, most of my wheels etc… It doesn't bother me too much but then I'm the sort of bloodyminded sod that'll do everything in his power to destroy anyone who tries to rip me off so it concerns me less than it might do. Ebay offers more protection than most people think provided you're prepared to jump through the hoops to use it- they make it deliberately difficult to do but get it right and things tend to go well.

Wot Northwind says, similar experiences (and attitude!) here

You have to be prepared to take the rough with the smooth though, only a fool would expect all 2nd hand buys to work out

Like northwind I use a lot of second hand kit and would also get fairly medieval on people who try to rip me off, if it's expensive kit (ie a frame) try to view it and inspect thoroughly – you'll soon be able to tell if the guys a muppet or not. There are good deals to be had but like the others say if the ad is ropey and they do not know their arse from their elbow leave well alone.

Cheers- looks like I'll check out some second hand stuff then 🙂

From experience I'd avoid wheels and forks (unless you can get a good look inside them before buying), other than that fill your boots! Almost everything bike related I have is second hand.

Buy from someone who's bought an expensive bike "to get fit".

If you turn up and a fat person answers the door – you're on to a winner coz they won't have ridden it and it'll be in top condition.

Look in local classifieds and on Gumtree.