The amount of options that one gets on an amp from Glenn will make the prices vary greatly on the OTL amp.
You can get the basic for $750 or you can start adding stuff and get well above twice that price.....so that is probably the differences in the varying prices you have seen.
Not to mention that many times tubes are included in the sale,which can dramatically increase an asking price.
All very good points! I think that adds to my point of how hard it is to find the GOTL you want on the used market!