It won't help you right now, but if you want to pick up some extras (say, one to keep in the bag, one to leave at home, one for the office, etc) sometimes they'll show up in the CDW outlet for cheap. I picked up 5 of the 65W Thinkpad adapters for about $20 each a couple of months ago. As of today looks like they have 90w, 170w, etc also available for much less than retail.

As with anything B-stock, its best to contact the reseller to inquire as to why its being sold in the outlet.