Typically your suppose to be certified to buy high power motors.
Sometimes vendors, especially at launches, just assume you are already certified or are buying a motor to use for your certification.
I have seen the same from on site vendors.
I bought some high power motors from online auctions, no questions asked.
Certification requirements as far as buying from vendors is self policed but I think there could be trouble in these same vendors getting motors from manufactures if word was to get out.
There, as far as I know, are agreements between major motor manufacturers/dealers and TRA/NAR not to sell to non certified flyers.
Oh and check out tripoli.org also
Nar and Tripoli both certify high power.