Vehicle prices in Thailand, both new and second hand have little correlation to the rest of the world. TIT, it is what it is
Prices of ALL bikes went up due to the recent tax increase that the Thai government imposed on motorcycles. It's been covered pretty thoroughly in this thread:
Motorcycle Tax Increases!!!
I was going off old prices in my last post. Here are the new 2013 prices for Kawasaki (oddly enough the prices on their main website are still out of date...)