If all your stays are going to be done by using your points to make HGVC reservations then it doesn't matter where you buy.
But if you want to often stay in Orlando during platinum in a 2 bd then buy that. Each year you use your own unit instead of using your points you'll saving money. It is a big deal? NO, but why use your HGVC points for $60 if you can make a free reservation at your home resort.
Good Luck
PS this advice assumes that we are not talking about Hawaii. Where the prices are so very much higher that I can't ever recommend buying there, unless your travel plans are very very strict.