Don't know for certain, but I am pretty sure that Benchmade enforces minimum sale prices at their authorized dealers. This is why you see the same price at so many of the top retailers. Some might give free shipping or throw in incentives like stickers, pouches, gloves, cheap knives, or whatever as incentive to buy from them without giving a discount.
So when you see every familiar dealer selling the same BM knife for, say, $252 and someone else has it for $179, and both are BNIB, that is a pretty good indication that something is off on the cheaper site. Could be that a legitimate dealer has some old stock priced at, say, $239 and they are cleaning it out for that price. Not likely to be a big difference in prices, though.
Another thing might be to find the contact address on the sale site, then look it up on online maps. Might be a field, a shack, or a crack house, so that might tell you something. Do the satellite view and street view if you can.