Try to get to a shop that specializes in muzzleloaders, not a shop that carries some muzzleloaders as a side line. There are some really fantastic guns out there, that are hard to find at the shops. I hate trying to buy/order a gun by just looking at pictures and descriptions. Do you want flint or perc, or inline. Will you want to use heavy hunting charges or mostly plink and use it as a possible follow up shot with your regular muzzleloadr gun?
I am fortunate that I live about 60 miles from Dixon's Muzzleloader shop. At any one Time, he probably has 10 to 20 different model side lock pistols in stock.
Some folks rail against the Spanish made guns. However, there are some new lines of guns made in India, (as incredible as it seems) and they don't look bad and have been getting fair to good reviews.
I have a fair collection of black powder pistols. From flint to perc lock to inline and revolvers.
Over the years I have managed to pick up some odd ball production guns that I have never even seen pictured in a catalogue. How about a Italian made kentucky style percussion pistol, with a solid brass rifled barrel. Or an Italian made 36 caliber box lock perc target pistol, with Olympic international style target grips. (It was cheap too, only $65.00 brand new in the box.) There are a few pedersoli pistols in catelogues, that I understand only perhaps a dozen or so have been imported to the US.
When you get up to the fancier production pistols, sometimes it is cheaper to get a custom builder to make one for you.