I think that a quick criuse of these forums will find a whole bunch of people who will tell you that they can get you hour building at $40/hour in new aircraft (usualy in Florida).
The fact of the matter is that most of the cheap hour building packages in the USA will supply you with a very old aircraft at a moderate price, the big problem is the "other costs" such as airline tickets, hotels, car hire etc.
The add on costs usualy push the true total cost per log book hour up to around the £72/hour.
Some of the company's in the USA offer a lot to you and then fail to deliver (like the one I booked with for the multi & IR that did not have a twin when I turned up and the outfit down the road who were just as inept).
Eventualy I went to a third company who did a fantastic job with a very good aircraft but charged 30% more.
If you get a good company in the USA there are good deals to be had but if like some of the people I have met you get a bad one the true hourly rate can be as high as £700