SELL IT NOW WHILE STORES ARE STILL LOW ON STOCK.
Then go buy your PS3.
Wii isn't for everyone, not everyone enjoys 1st class in-house games, and 2nd rate everything else, so I dont blame the guy.
HOWEVER! You must admit you are selling it at the worst time. Online is about to get a lot better, DLC is about to be rolled out. The solid support from 3rd parties is about to be realised, WiiWare is about to be released, so you can be sure there will be games there that no one else will be able to play etc. Get NMH, and consider waiting it out til May before selling. My Wii was collecting dust for a good month, before I realised just how good a thing it is.