its not a bad deal considering you do not have to sign a contract to buy it from your friend. however you could get a comparable or better (personal opinion i guess) phone like the Blackberry curve or pearl for 99.99 or less new on contract

Are you eligible for an upgrade at all right now?

And do you like WM or used it before?

Im not really a fan, but 135 is pretty fair for that phone. If you wanna know what the market is like, look on ebay and see what they are going for.