I bought a Chauvet Obey 4, and from the quick research I'd done it seemed to be what I wanted.
Ebay purchase.
But when I tried it, it wouldn't run the lights I had, so I looked a little harder, and found that the 4 would only run four channels- I needed eight.
A few emails later, they swapped it (plus a few pounds difference) for an Obey 40, which is fine. It's what I should have ordered in the first place.
Caveat emptor, sure, but they certainly come up trumps when I didn't emptor enough at the choosing stage...Thanks, guys.