If you're after a flintlock smoothbore at a "budget" price, you can try to find a used piece, or consider the Made-in-India guns that appeared on the market a few years back. Otherwise, new Pedersoli guns and anything custom (or "semi-custom") is going to start around $900.00 and go up from there!
Many guys disparage the quality of the India guns (mostly guys that haven't owned one!) but the ones I've seen in use are quite reliable. Are they the quality of the Italian or custom guns? No, but for someone without a ton of bucks to spend, they are a good starter gun.
This guy sells them, and for an extra $50.00 will tune up the lock, polishing and hardening the internals, etc.:
Another good source for these is Loyalist Arms up in Canada. They buy the components from India, then do quality control on the parts before assembling the final gun. Great customer service, too:
Don't be afraid of flintlocks! They are easy to learn to use, and are WAY more reliable than many people think...!