Ok, not much experience in black powder
I want something for just the toy factor. I won't be hunting with it just something to slow down and broaden my gun collection. I was thinking even one of those naa companion ball and cap kits. Maybe a bp carbine of some type. Probably only shoot it from my back porch to the woods. About 30 yards max! Pistol/rifle - traditional/new age. Just somewhere to start.
Not looking to spend allot of money either. Maybe 4 to 500 bucks Tops but the cheaper the better
For that money, I would look into getting a Pietta replica of the 1858 Remington, .45 cal revolver. Maybe go stainless if you're new to the black powder game. Fun guns that are forgiving to the beginner but still a challenge. If you find the load your particular gun likes, you can expect to roll beer cans at 25 yards, depending on the shooter's skill of course.
Here is a recent thread where the OP gives a good write-up of his experience with one.
That particular model will run you $450 from Cabela's. Plan on spending another hundred dollars getting set up with the various accoutrements necessary for black powder shooting. Perhaps a little over your budget, but in my humble opinion worth saving a few extra pennies to do it right and get everything at once.
You want something just for fun? Get a flintlock rifle. I have a .40 caliber which is great for targets and plinking. It's a little small for hunting.
Flintlocks are just, well, fun. The learning curve is a little harder than a caplock, but mastering it is much more satisfying. Did I mention that they are fun?
In your price range look for a Lyman GPR flintlock. They are well made, and a cheap rifle will have a cheap lock, and that will aggravate the hell out of you. TC Hawkens are another good choice in that price range. The Lyman rifle are a little more "period correct" but either is a well made rifle that will last for a long time.
Go with a Lyman Great Plains Rifle. It looks the part, more than most out of the box BP rifles and makes a great decorator piece while you're not shooting it. BP revolvers are fun, but laborious to load and shoot.