Magnepan SMGa - what are they worth, best places to sell?

The glue that secures the, "voicecoil" wiring to the diaphragms, on the early Maggies, often fails(age/sunlight). Be certain to test them, before selling. You may avoid an unhappy customer.  Around $400 sounds correct.   I gave mine to a friend, after we reglued them.

thx, rodman ... they are running fine now but was tipped off to that potential problem by the Svc Mgr at Magnepan this AM

Generally speaking, unless the damage is severe, they only rattle at certain freqs and power levels(iow: once in a while).  Best way to test, is very slowly, with a sweep generator, at a decent amplitude.  Of course, the original owner(s), may have kept them out of the sun, in a controlled environment and they're fine.   Here's hoping!