Well, the title of the thread is "blackpowder handguns", so I wouldn't expect to be talking about longarms like the Kentucky or Hawkins rifles.
But, that doesn't mean not talking about musket pistols, even single shot ones.
So, my recomendations are to buy things made by Pedersoli, and to buy them through Dixie Gun Works. Dixie wasn't my first choice when I was looking around the internet for places to buy guns, but they were the only ones who I could count on to buy the very specific models and manufacturers I wanted. As I looked at their website more I also saw they allow user reviews, which helps as well. Now they are definetly my first choice.
Other manufactures I would recomend are Ruger, though they're a bit pricy and they don't make historic reproductions. F.L. Pietta is good, and Uberti is supposed to be even better by a small margin.