You can insure it in his name if you're actually married. It might not be cheaper, though, if he's got car insurance in his name already as he may possibly have to start off with no no claims for a motorhome/campervan. I did, although I have full NCD on my car.
I can only say that I'm with Adrian Flux. I've insured 4 vans with them over the last couple of years (don't ask!) and have paid approximately £180 each time. You get a discount for being a member of an owners club or something - I think this web site counts.
This is what I paid in April.
2003 Symbol, 71 year old only driver, Caravan Club (Equity Red Star) £212
I could have got it cheaper, £189, but company was registered in Malta so didn't bother.