[Arran]

 One thing to keep in mind with many of these 1941 models is that they used a Tenite plastic escutcheon, pushbuttons, and knobs that are often warped, shrunken, or otherwise disintegrating, and you will be looking at another $60+ to replace those with reproductions. Then you have the rubber/gutta percha covered wiring which is usually shot, and last but not least an open primary on the output transformer. This is assuming that the cabinet is in good shape and does not require any refinishing or repair work. So no, $90 is too much money in my opinion, I would try to pay as little as possible for it, maybe no more then $40 $50 if you really like it, preferably less.
Regards
Arran