Since you are certainly aware that there is no type rating necessary to fly aircraft under 12,500 lbs in the US, you could answer the question yourself: 0
...and mostly you don't need a ATPL here - and if you do need one for you IFR job, you'll need the 1,200 hours FIRST ("frozen" not possible)
However a fancy type rating in a Schweizer or R22 shouldn't be a big deal once you have flown it a few hours. I'm not sure if you could even go to Bristow and just get that type rating over with.
Again, its not more complicated to FLY "european style" its just that everybody has to learn almost how to BUILD an aircraft or how to navigate around the world without a GPS (for a helicopter ATPL!) first (I got the Bristol.gs study material already).
Ever thought about how it is possible that so many Jets and Airlines land in europe every day with the same accident rate?
No bad blood, but I try to keep my sarkasm going
! (Americans unfortunately mostly don't understand it) I think if europe would get over the requirements to join their old boys club and the faa would require a bit more knowledge on systems and components we would do alot better!
...one last thing that occured to me regarding my calculations from earlier: disregard the cost of living, first of all you have to eat and sleep in the uk too and its even cheaper to live here!
So substracting travel you have still £40,000 left for type ratings and still be dual rated and probably with alot more hours through flight instructing too!