Manufacturer refurbished Wi-Fi + 3G Nooks are $99 at eBay, with free shipping. These are "direct from Barnes & Noble".
No idea how long these will be available - B&N seems to do this (sell mfr refurb Nooks via eBay) from time to time, and the deal usually seems to be around for a while - until some quantity of Nooks gets sold.
I don't use a Nook, and don't follow all of the specific Nook models, but $99 for the Wi-Fi + 3G seems to be a pretty good deal. I'm actually tempted myself, just to try out a Nook, but I'm still pretty happy with my PRS-300.
Anyway, the link is here:
http://cgi.ebay.com/NOOK-Barnes-and-...21263713231392