You could do a lot worse than starting with recommendations from the dealers for the European factory-built aircraft (though they have to be delivered as kits in the US):
shell
AutoGyro Sales, AutoGyro Dealers, MTOsport Sales, Calidus Sales,
Assuming you aren't a US citizen, quite how they would deal with all the TSA and Visa stuff I don't know.
... or you could try one of the UK schools!