The 18-pin zero insertion force (ZIF) sockets are becoming expensive and difficult to find. The once common part made by the TEXTOOL division of 3M is still available from Digi-Key. It is the gold plated (literaly) version (3M part number 218-3341-00-0602J) and the cost is around $18.
A 24-pin Aries socket is available from JDR Microdevices, JAMECO, Digi-Key and others. The Aries part number is 24-6554-10 (tin plated contacts) and the price will be in the $8 range. Simply ignore the extra 6 pins.