Electric Upright Bass Database

You could buy a back issue of Bass Player's December 1996 magazine.
There was a review of several commercial electric uprights.
The reviewer (Bob McCaskey) did a good analysis, and this could give you good hints for yourself.
Of course, the review is almost four years old, so many things changed, but it's a very good starting point.

If you're not already subscribed, I suggest you get a look at http://www.egroups.com/group/eub...
It's a mailing list exclusively devoted to electric uprights.
There are already 53 members there, who could help you a lot!  :)