I'm toying with getting a cheapo jump\play bike, and was wondering what the STW massive suggested . . .

It's mainly going to be used to biking with my son (3.5 – just getting used to pedals) around some parks, a few of which have some nice dirt jumps which I fancy killing myself on (it'll make him laugh at least).

I dont need anything particularly bomb proof or pimped. Ideally it'll have a few gears, and be a comfy enough for me to pedal about for an hour or so (so no bmx's).

Would a 24in bike be worth thinking about?

Any idea's appreciated, as cheap as poss

Merlin used to do some cheap 4X frames around £65, which would be good if you've got some bits lying around. I built one up for messing around and its plenty of fun.

Have a look at the Flow or DMR full bikes, great for the money, my Flow Myth is awesome (although thats the one they dont sell complete).

I picked up an Identiti Dr Jekyll off eBay for 75 quid and built it up with some old Deore/521 v-breke rims I had knockign about and the worlds crappest forks. Singlespeed with old Deore kit to keep the price down. Built it for similar reasons to you. Something to dick about on and learn to jump a bit.

Commencal maxmax, basic model is £300 new, seen them second hand for £100-150ish