I still think ;Buy and Sell; forums are the best place to look for pricing. I wouldn't rely on eBay too much; some prices go sky high for more than they're worth at times.
The "value" of something is just what someone is willing to pay for it. To arrive at a realistic value for a particular piece of computer equipment, you need to collect all the information you can from as many sources as possible. As a "fallback" position, what can you get it for at a local retail dealer? Are similar items selling on eBay, and what are the final prices in Canada? In the US? Are similar items selling on buy-and-sell, and if so, for what price? And, of course, don't forget ehMac!
In other words, put a little work into it and don't grab the first deal you see. You'll save enough to buy some extras!
Cheers :-> Bill