(ET) General value question

["GWaugh" <GWaugh wowway com>]

I don't have an Elec-Trac, but have been following along as best I can for 
some time now.

In a couple weeks I am attending an auction at which are two machines---I 
believe an E-12 and an E-15.  One of the two was used routinely until 
several years ago, when the batteries quit.  It has been shedded since.  I 
know nothing about the other.

What, oh those of you with crystal balls, are such machines worth?  Let's 
assume reasonable physical appearance (not rusted through, etc.), bad 
batteries, functional deck.  I I play around with a lot of old equipment 
(tractors, garden tractors, hin n miss endines, etc.),, so I KNOW no one can 
give me an actual number---but even a wide range would be appreciated.

TIA,

Gene Waugh
Elgin, Illinois USA