Frankly, I think the $2500 target is just someone's personal allowance for a gun and it's unrealistic for this type of project.
For a finished gun from such an ensemble of craftsmen, a target of $10-15k would be realistic in my opinion. And I would say that would be a non-engraved gun. The goal isn't to make as cheap a gun as possible. It's to make a fine as gun as possible of the same design as the Lefever. Anything less and it would be a total waste of everyone's time. I don't think anyone that had a skill to contribute would have any asperations of competing with Huglu.
CSM is selling just barrels for approx $2k. That would be a safe baseline for barrels for a this project. I believe he may be outsourcing those barrels. I'd find out, and contract them, if possible.
A good piece of wood costs $500-1500. Even the labor for a machined stock with final hand fitting and checkering has to be a $1000 bill minimum. Another $2-3k on the gun depending on wood quality.
Now the hard part, the action. Just the machine time, not counting setup, tooling costs, programming, designing/tolerancing, reverse engineering, or whathaveyou...I'd estimate you'd not find a shop that would do it (for a legitimate job) for less than $1k, for just machining the frame. No guts, no forend. I'm talking numbers like 50 pieces. You want 100, 200, 500, 1000 you get different prices. The guts and forend are probably easily as much as the frame in machining costs. So, say $2k for a pile of parts that don't fit yet, are not polished or blued/casehardened. If a guy spent 10-15 hrs fitting and finishing, call it another $500-1000 (this is one of the skills we seem to all judge critically, so you'd want it well done)
I count about $8k above and thats without recouping any non-recurring costs from startup. Many 10s of thousands would be spent in getting this project off the ground, if wages were being paid for that, even menial wages.