What do you mean by entry level?
Inexpensive? Yes, Traditions makes some decent quality, inexpensive flintlock long guns. For the money, Lyman's Great Plains Rifle and Trade Rifle are a better value; more expensive but lifetime quality.
Easy to learn and operate? No. Flintlocks appear to be simple, and the basics are pretty easy to pick up. The problem is that the fine points of tuning a lock to get the best performance and/or solving problems with the lock are not. The less expensive the equipment, the more likely you are to have problems, and they can be significant.
With an inexpensive 'entry level' gun you don't have much invested if you find flintlocks are not for you. Unfortunately, it's also true that with those guns you're more likely to have the kind of problems that frustrate you and cause you to give up the sport.