What is a sumo nine worth today?

I have a sumo nine had it for years still in plastic in the box can anyone tell me about it and what it be worth today?
There are six listed for sale on hifi-shark. Prices range from $550 (Audiogon) to $1200 (EBay). You can expect to get the minimum for it - but probably more if you can wait! 
There is quite a bit about it on audioreview.com from different sites!        An excellent amp from the late James Bongiorno (SAE, Dynaco, GAS). It runs hot (fan) and puts out 65 wpc class A. Ten output transistors per channel. Designed and produced about 1980. Can drive difficult loads (electrostats, planars) with ease. Sound quality competitive with today's four-figure amps. A true classic design!
Keep the Nine, get a pair of Quads - old or new - and you will be more than halfway to audiophile heaven!
Modernizing some of the innards (parts wise) is usually the way to go with these older amps.
Its worth a fortune hold on to it for life.
Did somebody spike your cocoa EBM?
I think I'm smelling some sarcasm from ebm.  It is a good amp though, & well respected back in the day. They've had one at a local shop for about a year now. If I remember right, they are asking $1200. 
I have a Sumo Electra preamp to go with it.  When it works, it has a nice sound to it.