with the need for a flight to get there and back it's just too expensive so my kids have gone to US gymnastic training camp at Mt. holyoke college - I have found it to be a really great program and if you haven't gone then I would suggest trying it too - it's really great!!
They have Olympian, Olympic coaches and more come in and work with the kids too.
My DD is there right now and has gone for the last 5 years - she loves it. My son who is too old to go now went from when he was 10 yo to when he was 16 and love it too.