$1500 is a lot of money for most of us, but not so much in the custom flintlock world.
But you do have "finished" options.
You could look at Pedersoli (factory produced). They are far and away the best built, best finished and some cases down right awesome looking rifles in mass produced market.
(Pedersoli)
Then there is the semi-custom rifles produced by TVM. I say semi-custom because if five guys buy the same model there will be no doubt they came from the same place - maybe a little different here or there (not a "carbon copy") but close enough that you have to look fairly close to see a difference.
You can check them out here
(TVM) You can go from pretty basic for 700 or 800 bucks, or you can "customize" and make a pretty good dent in your 1500 bucks.
(edit - I just had a look and their prices have gone up a fair bit since my last serious look - your 1500 bucks would get you a "standard rifle" from them now)
There is also builders like Tip Curtis (no website, but someone can give you info on him). He can provide you with a fully functional rifle "in the white" - so basically you just stain/seal it yourself plus do the metal treatment of your choice (cold blue, rust blue, rust brown or just leave it).
His price ranges would be similar to what you would see at TVM but it would be a little more unique.
Those are the first three options that come to mind - I'm sure others will chime in with other suggestions.