How to value a used CD collection?


I have a pal that digitized all his CD's and is looking to sell them.  Approximately 500 high quality jazz CD's.   I expect he will be looking for a price for all of them.  I'd be keen to have them, but have no idea what that sort of collection is worth.  Maybe $5 a CD?, but he has lots and lots of stunning recordings that cost $30 or more.  Any insights would be appreciated.  Maybe I should just asked to match his best offer and see what happens.  

Any insight would be appreciated.  Thank you, Mark  
whitestix
Secondspin.com takes less of a slice of the pie than either Amazon or eBay.

Reverb is cheaper still but not as well known as a site for consumers for buying used media ... Yet.

However one downside of secondspin is that just about ALL the cds on there are dirt cheap to start with.
David12 is correct, of course. What the friend is planning to do constitutes copyright infringement. Assuming, that is, that the material was copied to a computer hard drive as opposed to a medium for which royalties were included in the purchase price (e.g. Audio CD-Rs or some digital tapes).

Regards
-- Al 
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