The DT175 is actually a 125cc bike. So no worries on the 150cc limit. There are a few on the island now.
These are the ones they sell in Belize:
http://www.marelcobz.com/yamaha/motorcycle.html5,200 isn't a terrible price if they are in good condition. The yama's and honda's sell for $7,500 to $8,000 new. $5k - $6k used here on the island...and after two years here they are well weathered from the salt air.