http://cgi.ebay.com/TWO-UE-SPIDER6-U...item3a5befe512
Complete UE 1/8 diffs and cases- should sell for about $150 usually ( normally about $250-300 new ).
If you just want to buy the cases ( new ), then only UE sell them, and only to USA residents, so... impossible to get basically, only if they appear for sale on ebay or for sale on a forum.