We've had our c-o-w about 6 years now (and we still have the same worms!), I looked at other designs and making your own, in the end I bit the bullet and paid up because of the ease of use.
We rotate our individual trays about once every six weeks in summer and slower in winter (maybe a couple of times). Whatever you get I'd base it on being able to stack and rotate the 'trays', its so easy.
Oh and we've moved house twice since we bought it and the removal men haven't minded it in their vans! LOL!
