Refurb D5100 for $499 ($569 w/ kit lens) at Cameta:
http://slickdeals.net/f/4222670-Niko...ping-at-Cameta
I've looked at Ebay and Craigslist and low end used prices are typically in the mid-high $400s, so the refurb deal (which has a 1 year warrantee) is probably a better bet than trying to save $50 from a seller thinking their used digicam is made of gold.