Well
It seems you've made up your mind then.
If you want, the vendor here in the USA will put a 700w in a 700c rim and charge you $70 more for a total of $290 including the shipping. (that's the highest wattage motor he carries.)
OR
Go with the Chinese eBay guy. (just remember, any problems from the Chinese items, will be if it breaks, it would cost you more to have it shipped back and forth from/to China to have it fixed, then it would be to buy a new item.)

Just my .02