Help with selling GAS preamps

Hi, I just discovered this site while researching the preamps my father gave me to try and sell online.
I have been having trouble posting them on Ebay. Perhaps someone here can help me? Should i make listings here and is that better? I did not see any listings for any GAS company electronics.
I have 1 Ampzilla 2 Son of ampzilla and a Theadra
Any info on these systems would be great help thanks!
The Son Of Ampzilla listed for $800.00 when it had its run.  The Ampzilla was around $1200-1300.00 and the preamp was around $800.00 when new.   Some of the best solid state at that time. 
jjaffe, where are you located ?