I've bought and sold more that a few Busse's. Never sold for less than paid. Mostly even, but some, a profit. I'm not into collecting much anymore, but more into users. As soon as I pick up one you can tell how it fits and suit the use that I have in mind for it. If not, it gets passed on for pretty much the same price. If it does, it gets the snot beat out of it.
I've sold a total of 3 Rats. I use them em all and these 3 were duplicates of users I had. You really don't need duplicates of Rat knives. Well, not the standard line anyway. When I bought, the standard line was it. You aren't going to break the first one, so the second is pretty surpurflous. A little different now with the limited runs of course and I DID buy 3 Inficoots ( pretty much the first thing different from the standard line and limited quanities). BTW, they went for cost+shipping+no wait. (The standards, not the INFIcoots LOL )
Also, Busse has been around for 20 years, Swamp Rat for around 3 or so. There's simply a LOT of Busse's out there, along with the different styles over the years (Straight handles, Ergos, and now the Fusion), then the Variants, LE's, over runs and Lord knows what else. There is just simply more to be had.
About the only Rats I can see coming up for sale would be some of the limited runs that someone might get more than 1 of. My users I couldn't dream of selling. For what? I use them all more than a few times a week and I see no reason to sell them. I think the majority of Rat owners are like that. You have an excellent tool, why would you get rid of it?
Still, keep looking. Ya might get lucky.
Rob