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
A thousand for all assuming they’re in perfect condition. The most profitable way is to sell them in small lots on eBay. Or in some cases, if very collectible, rare or whatever, one at a time. 
Ironic that an audiophile mentions dial tone phones. Have any of you talked on one lately? In the hallway of my 90 year old home there is a black bakelite dial up phone from the 1940’s. We rarely use it but when you do the first thing you notice is that the sound quality is exceptional and that everything else you use for a phone sounds like crap. Even people on the other end will comment that it sounds better to them than any cell phone or cordless land line phones.

Agree with geoff. eBay is the way to go. Most sellers are getting $4-8 for typical pop/rock CDs of decent quality.

Some may think that is high but there isn’t another medium out there that presents that sort of value in music that you own.
jafant, 
I been been traveling for a while and haven't followed up on the transaction.  The best arrangement that I can see is if he sells 100 CD's off at a time, that I get a chance to match the dealers's offers.  They are all excellent CD's and I can peddle them off individually.