1.) What are the laws reguarding the sale of blackpowder pistols? Can I order one throught the mail? How old do I have to be? (probably 21 but I hope 18 is good enough)
It varies by state. Muzzle loaders, including cap-and-ball revolvers, are generally exempt from the federal laws requiring sales through an FFL holder, etc., so you can order cap-and-ball pistols and have them shipped directly to you in most places. Some states, however, have state laws prohibing such sales.
Are there different laws for blackpowder cap and ball and blackpowder cartridge?
Yes. The federal laws exempt guns that do not fire fixed ammunition, e.g., muzzle loaders and cap-and-ball revolvers. If it fires a commercially available fixed cartridge, it is regulated. It doesn't matter whether there is smokeless or black powder in that cartridge. For example, all of the replica single action "cowboy era" revolvers currently on the market (such as the Colt Single Action Army and clones, Smith and Wesson Schofield, etc.) are regulated just like modern firearms. You can only purchase them across state lines from a licensed dealer in your own state and only if you are permitted by law to purchase a firearm.
2.) Does anyone make blackpowder cartridge pistols for around $250 or less?
I'm not sure what you mean by "blackpowder cartridge pistols." Any pistol that can shoot smokeless cartridges can also shoot blackpowder cartridges. If you are referring to cartridge firearms originally sold in the black powder era, such as the Colt Single Action Army, the answer is no -- you can't buy a new one for under $250. Entry price is around $350 for the least expensive Italian imports, with better quality guns selling for anywhere from $450 to $1,000 or more, depending on manufacturer, model and finish.[/quote]
Does any company make good black powder cartrige ammo?
Yes. Goex makes excellent black powder cartridge ammo at reasonable prices (it's available from Powder, Inc., and some other Goex distributors). Other companies like Ten-X, Ammo Direct and others offer cartridges loaded with modern black powder substitutes.
3.) What is a decent cap 'n ball revolver for around $200?
$200 is around the entry price for a decent cap 'n ball revolver. For about that price, you can get an Italian made steel-framed (blued) replica of the 1851, 1860 or 1861 Colts, or the Remington "1858" (New Model Army). Cabela's and Dixie Gun Works have good selections available in their catalogs and via their websites.