Reliable source to find out real value of titles?

[jee]

Hey folks,

I am finally ready to start selling a large amount of my collection. Unfortunately looking at prices people are selling titles for on ebay is not entirely reliable. D
Many prices people ask on there do not reflect true value. (Many prices appear inflated or unrealistic)

I intend to sell here on trade forums before offering titles on eBay. Just wanted to see if anyone can recommend a good source for ascertaining realistic values.

Thanks.

I will start listing in the trade forum within the next day or so