I'd vote for the 42 as well. You can acquire a VERY nice one for much less than your budgeted amount and you will find it fits the hand quite well for carry afield and most are wonderully 'shootable'.
For a double, I'd try looking for an Iver Johnson 'Skeeter' or a Nitro special, both American and both good servicable salt of the earth guns. Either may require a bit of looking, but they are out there and a good quality shooter should be well south of 3K even if its been restocked with decent wood &/or zooted a bit. Perhaps we can get Chuck to post a pic of his .410 as an illustration of what can be done with a Nitro.
FWIW, predicated on the chamber length, I have found the new WW AA 2.5" Sporting Clay target loads of #8.5 shot to pattern very well in both 2.5" % 3" chambers and the best 3" ammo that I have patterned is the Fiocchi 11/16oz. # 7.5's, the later having a wad that is unique to that load as far as I know and it actually contains the whole shot column. I wish it were available for reloading, but it is not.
Please let us know your end decision and result.
