Beg to differ. It may be a little high when you add shipping and FFL fees but it IS new in box. We aren't talking about a lot of money high either. Take the "parted out" price and add them up and see what you get.
new ML barrel and forend $100
new slug barrel $50
new frame $100
new stock $25
Those prices are conservative if you search through the GBO classifieds.
This Huntsman combo has a SB1 frame, you are not going to get 100 for a SB1 frame when you can go down to wally world and buy a brand new complete shotgun for $115 with a barrrel and stock with no FFL fee. Now, if it were a SB2 center fire rifle frame, you could possibly get $100 for it. The SB1 frames might bring $50, When you add a FFL fee of possibly $25 on both ends, possibly costing you $100 total. If it started at $100, it could cost you $150 for just a frame after the FFL fees on both ends. They become less desireable when you can pick up a whole shotgun at WW for $115 vs just a frame for $150 that you would also have to pay a shipping charge on top of. If you bought the WW shotgun, you could turn around and sell the stocks and barrel for $75 total, possibly more, AND you don't have to pay a FFL fee on either end to sell barrels and stocks.
Those plastic sights are worthless on the muzzleloader barrel, I know because I have a 2003 Huntsman that had them and upgraded the sights to the current (since 2004) Williams Fire-Sights. At the time (2005), they were around $30 for the set + shipping, I'm sure that Remington is probably got them marked up quite a bit from that old price.
I agree with your other prices on the stock and both barrels, but stick to my $225 tops for the package.
He has a flat rate shipping charge of $35 + the original $275 + $25 (approx) FFL on his end, + $25 (approx) FFL on your end = $360.
Any item for sale is only worth what someone will pay for it, the original poster said "this has been on Gunbroker forever"! Not sure how long forever is but I imagine it has been awhile. He may get someone to buy it at that price, but it might take two "forevers" to sell it as well.
My $0.02, and worth every penny.