Many people put up a schematic for anyones for general use or information.
They may or may not have actually gone the extra mile and mapped out a circuit board for it, if they have, just for their own use, then they might offer it also for free, but if they are expected to provide one regardless, then I would expect this to be paying proposition.
Then we get into the realm of prototyping/marketing, which many do not want to bother with, especially for small run items.
There are many other aspects such as whether people prefer a design in SMT or through-hole components etc.
Schematic Design is one thing, PCB design is a complete other.
Also the builder may have used a one-off proto board version for the original.