My opinion is that you are much better off spending your money with one of the Florida factory PPL schools, I won't mention any names for risk of starting a war. It will almost certainly be cheaper than any other route and the Florida factory schools are experienced in getting the visa business sorted for you.
Philip, just to clarify, hour building is something that you do AFTER you have a PP licence. After getting a PPL (which is just a mark of a minimum standard achieved) it is then necessary to build up an experience base hence the term "hour building".
To undergo training for a licence in the USA, you MUST have a visa (not a visa waiver) It is just sheer stupidity to go on a visa waiver.