Mike, can't agree with you. There were some actions, where older H&H rook rifle in fair conditions were worth more, than your estimation
http://www.auctionarms.com/search/displayitem.cfm?itemnum=9057481

And the same Royal 295/300 caliber for 2,400 GBP
http://www.sothebys.com/app/live/lot/LotDetail.jsp?lot_id=159245894

IMHO overbored smooth bore barrel rook rifle in such condition has to go 1/2 price from original, ie aprx. $2,000. I allways wanted very light single barreled .410 gun to shoot great snipe over my dog, but seems rifle converted to smooth bore gun is not what I'm looking for.

Geno.