Some rambling thoughts:
Seems Most experienced Flint enthusiasts lean toward custom guns with high quality locks like Chambers or L&R and barrels by GRRW, Colerain and others. Nice custom rifles run from 1500 up and are going higher daily. Factory rifles start at 500 and go from there. Right now the Lyman Great Plains (GPR) Flinter in .50 or .54 are hot. Many consider them the best for $ and have a good rep for , style, performance and ultimately price out at 700 new. Early GPRS and the newest signature GPR by pedersoli seem in big demand.
Both CVA and TC stopped making ML Hawkens long ago ect and prices are up there, Beware that the TC "lifetime warranty" has passed and many locks are starting to fail. Small parts are very pricey plus many feel the style was never right. CVA and Traditions are ok for average rifles.
There's a host of ML flinters made during the previous BP "boom" . Italian made are considered higher quality than Spanish. I avoid Spanish stuff since an unfortunate incident with some early stuff made there
We seem to be in a BP revival right now due primarily to gun control issues so study the field and choose wisely!