Have you checked with KEH.COM or one of the other big outfits that buy used cameras? They seem to offer about half of what you could get selling the items yourself, but that might give you a guideline on your gear. I'm looking at possibly buying a used D5100 to see whether I like that size form factor, but I don't plan on spending more than about $300. Right now, there is one on Nikonians that the seller has listed for $350, so that may be another indicator you can use in pricing your stuff. With the D5200 right around the corner, I expect the prices for older models to keep falling over the next few months. I now use a D90 and was going to sell my old D80 until I discovered that it had almost no value on the used market. I'll be giving the D80 to one of my friends or relatives.