How much should I sell my second-hand Nikon d80?

It includes the d80 body, Nikon camera bag, Nikon li-on battery pack, AF-S Nikkor 18-135mm lens, AF Nikkor 50mm, memory card, an improvised macro lens for extreme close-up shots, manual, CD, cord and cables.

I've probably had it for 4 years.

500-700

The only thing you have of value is the camera and two lenses. The lenses are going to hold their value more than the camera. The zoom lens should be worth $200 and the 50mm lens sells nearly $100 used, which is incredible as it is not much more than that new.

I'm thinking $500-600 might be about right.

Do a search on eBay on their completed listings for the D80 and see how much they are going for, which should be helpful in assessing your value.

Check out ebay to see what they fetch.

If you choose to sell it on there then split up your kit - don't sell it all in one lot.

The 2 lenses are both desirable and will go for a higher price sold separate so sell the body plus batteries, charger, memory card, cord, cables, CD manual etc as one lot; the 50mm as a separate lot, the 18-135 as a separate lot. Don't know what an "improvised macro lens" is! Maybe sell that as lot #4!