In reply to tobykeep:
Ben's is pretty good but a fair bit more than £7 if I remember correctly.
Snowdon house the other end on Nant perished sleeps about 18 iirc and was pretty cheap.
Just checked their website and it's changed a bit so now sleeps 14 and costs £295 for the weekend. There is camping space there so you could put a few in tents like we did when I took a group there ages ago.
Post edited at 20:00