No kidding, after recent events I wouldn't touch a cheap Ubisoft game key for any system, no matter how little I have to lose at $4.50. It's just not worth the hassle. Not to mention it wouldn't shock me to see console or account bans come down from Microsoft or Sony if Ubisoft whispered the right sweet nothings in their ear.
Ubi doesn't care that banning the keys doesn't hurt any scammers profits or that it only hurts otherwise "good faith" purchasers of discount keys, they've shown they'll revoke your keys at a whim and without even telling you (before or after the fact).
So, thanks but no thanks. For now I'll be sticking to legitimate retailers offering discounts, and none of these "too good to be true" sub-market value offers.