Fair Price For Extang Solid Fold?

I'm in the market for a bed cover and found a local CL ad for an Extang Solid Fold advertised in excellent condition asking $475. I don't want to low ball the guy but it seems like the sold used solid folds on ebay have been fetching somewhere in the $300-400 range (a lot of them were OBO so you see only the asking price) and on here it looks like a lot of the asking prices were in the $350 range.

What do you think would be a fair offer? I'm kind of thinking I might offer him $400 but the last time I tried to negotiate on CL based off what I could find as the going market price the seller was totally offended and totally didn't want to negotiate.

 

In case anyone looks for this info in the future, I offered $400, he came back at $450, I didn't feel like pushing it over another possible ~$25 so I just gave him $450 for it.

 

Where are you located?

 

Wisconsin