Every time this discussion comes up advice will be given to spend a lot of money for a quality firearm and there's certainly nothing wrong with that if the budget is there. It kind of bugs me that there is a certain mindset that if someone new to flintlocks starts out with a cheap gun they will have nothing but frustration and disappointment. There's going to be a learning curve regardless of what firearm you start with. Maybe that's less with a higher quality gun. I can't say having never owned anything but cheap flintlocks. They've all worked to my satisfaction.
A lot of guys might be like me and not willing or able to spend a lot at first especially when you don't know how well you'll like a flintlock. A year and a half ago I bought the first muzzleloader I ever owned. It was a $300 Traditions Deerhunter. I have not regretted that choice as it allowed me to get my feet wet without a big investment.
It just so happened that I found that I did like shooting these guns and now own 4 other flintlocks, make my own powder and cast my own lead balls. For the record none of my black powder guns are expensive high end models but I still enjoy them and shoot them a lot.