It's all a matter of time, place, and availability of the funds at the right moment.
The great bargain buys are remembered because they are so rare. And you have to search a looooong time to find them.
As to the used gun shops and pawn shops, how large/active is the muzzleloading crowd in your area? The larger the group of interested people, the harder it is to get a great deal - just too many people chasing the same thing. If there are no active clubs, shooting ranges, or hunting groups in your area, then the "demand" is less and any used muzzleloader gets priced lower and lower just to move it on.
The rest is just time, patience, and following all the leads.
There's a household auction coming up on the 29th that has an "18th Century musket replica" listed. What is it really? Who knows! It could be anything from an early import jukar kentucky rifle on up to a dixie Brow Bess. You just don't know until you show up to see.
But this auction is in an area that has a pretty active club, and a lot of other people interested in muzzleloaders. So there probably will be several people there to ... compete ... for it in the bidding. The only way to know is to spend the time/fuel to show up and see.
The best deals I've gotten over the years have been at events - rendezvous or trade fair. Many years ago, I picked up a NW Trade Gun with a rifled barrel on Sunday afternoon at a rendezvous. It had sat on the guys blanket with a price of $175, along with several other guns, all weekend. I talked/traded with him just after noon. And then several of my friends were upset, because I got to it before they could. (They couldn't read the price tag and had never asked.) Now I have a "list" of people I need to call FIRST if I ever want to part with it. And then I picked up a Brown Bess (Dixie) on Sunday afternoon at an indoor trade fair. It sat there at a big trader's table all weekend for $195. Nobody wanted to touch it because all the brass had been engraved with ancient Mandarin Chinese characters. Well, that price was less than just the kit parts, and I figured I could file them off or replace the brass. I still haven't done that. It's now my "prize" captured from Chinese pirates while sailing in the Tea Trade. An easy fit into the right sailor's persona. And then there was that Sile Sharps 1874 Business Rifle with 200 rounds of BP loaded cartridges ...
So, the "great deals" just take a lot of time and patience to find - and how much "competition" there is out there. You find the same thing with blacksmithing equipment, and most any items.
Just my humble ramblings to share.
Mikey - yee ol' grumpy German blacksmith out in the Hinterlands