Well qualifed shop, generally looking at a bronco speciality or custom shop.
If you had a good C4 and you found someone who wanted the C4 and had a current 3-speed. If the moon is aligned just right and you have the winning lottery ticket in hand, you could make money selling the auto and getting a worn out 3-speed put in.
But going for a modern 5-speed manual (AX15, NV3500, M5R2), just pull into the shop, leave the keys, pick it up when done. Done right, good parts. I would ballpark $5k. There are a lot of parts to source, you are paying for time. Doesn't matter if the time is turning wrenches or pushing buttons (internet search, making phone calls). And how many other things are they going to find while doing the conversion, and do the right thing and fix them while there.