"Obviously had a fantastic time" doesn't even begin to cover it. Pity I was on my own - rather took a little bit of fun away.
R22 SFH costs - I went with a school which, for an upfront $1500, charged $142 wet. If you bought fuel while away, you were reimbursed at the school's fuel rate of just under $2 per gallon, and I got lots of practice in refuelling the little beastie. Other school's rates were in the same ball park. Other costs, assuming you have a valid UK medical and PPL(H), are minimal. Charts are about $8 apiece - I got two of most of the areas I went to. Have you ever tried to refold a paper map one-handed in a small cockpit ?
If you're in LA or somewhere else with poor public transport, figure on hiring a car - $160 for a week's hire from Avis.
Accomodation - check with the school. Rainbow has a deal with a local hotel, as do most of the others, and a clean and tidy room will set you back the grand total of $40 / day. While travelling, most places you stop can recommend hotels at the $50 - $80 mark. Most I paid was $149, and that was in San Jose, but I was knackered, bored, pissed off and in no mood to haggle.
As for getting a US PPL, if you've never gone to the US, then it's straighforward. Go to an FAA FSDO, give them your UK licence and medical and a completed application form, and while you wait they'll provide a temporary US Airman's certificate so you can fly solo. This is the same as a US PPL, and is valid as long as the UK licence is valid. If you already have such a licence, then you can add other UK or foreign ratings to the licence very simply.
As for Rainbow, Rotorbike, the machines worked fine - no mechanical problems at all since they're well looked after. More than can be said for their premises, hope they look after the new ones a bit better !