The world is your oyster, there are lots of private companies out there. The price of a band varies from under £5,000 if you go abroad upto just under £8,000. The most important consideration is the aftercare, go for one with at least 2 years aftercare, 3 is better. Then location of clinics is important - travelling for the op isnt too bad but you dont really want to be all over the country for aftercare.
My provider is WLS Group, prices locations etc are listed on their website if you google them x