hard to say for sure without holding it, but from the pictures i would think if you had it on a table at one of the big sword shows it would bring $1500-1800.  I think if you asked 2k you would get interest and offers, if you asked 3k, or more,  it would sit. Blade is mediocre but real, mounts are interesting and "flashy"  but not Goto or top end.  It looks like something produced(the koshirae) in the late 1800's for sale to westerners. I don't think anyone would want to spend money for restoration, if you invested 2500 in it you would never see 5k from the restored sword.  So the buyer must like the sword "as is". I don't think you were swindled, the owner had no idea what it was, i think it was a fair deal and the sword will now be preserved and cared for (no more glue).  If you are worried offer it here for the 2k you paid, or a little more,  and see if it sells. Again just my opinion for pictures