Dragline, the cost of BP rounds isn't like the difference between .38 and .44 magnum. As far as I can tell .36 and .44 ball is about the same price.
The expense of BP revolvers isn't the balls, it's all the other stuff you are going to need (WANT actually) to make it shoot.
You have to have ball, powder and caps to make it work of course But you have to have a method of measuring the powder and delivery. Some use just a flask, but it goes from there. It's another world really.
I like BP revolvers because they are so archaic, historical and interesting. I enjoyed gathering parts and pieces from various sources, making my own loading stands, making my own "over the ball" lube, finding deals on Ebay...etc. Just fun stuff.
I don't know how much you've read about them, but even cleaning a BP revolver is its very own art form.
OJW