Hmm, don't know about Canadian legistlation, but atleast here if offer is something which should cleary be readen as error they can refuse to full-fill it. Meaning under on tenth of price, but not if they are like 10-20% under normal.
Well, refusing to fulfill it isn't that big a deal in that case, and I wouldn't cause a fuss over that. The bad scenario would be if they shipped you some other model other than the 4100PRAUS which was, in fact, a QWERTZ layout membrane keyboard and then you had to hassle with RMA, restocking fees, shipping etc....
The "good" scenarios would be either receiving an actual 4100PRAUS or having them contact you post-sale and canceling the transaction and refunding your payment.
It does say "Advertised Price" as if it's some kind of special deal. Who knows?