Here in UK there have been sales of each of these original arms within the last year. The Baker rifle is not uncommon, there were, after all, a pretty large number of them made over the years. Prices run around £5-8K for one in good to excellent condition. An officer's Ferguson rifle was sold last year by Bonham's for just over £13k.
I'm afraid that if the friend wants to soar with the eagles, so to speak, as far as rare and exotic flintlock replicas are concerned, he is going to have to stump up the $$$.
Making a replica of anything that is VERY expensive, if it be done correctly, is also VERY expensive.
tac