I bought a book of gps marks for Hervey Bay when I moved there, it cost me $6 and was a good deal.
it was pamphlet sized and fits in the tackle box.
Yes they were well known marks that were also on the net, but it saved me heaps of time searching new ground in a new area.
Id be happy to pay for a similar book if I was going to fish Raby Bay or Moreton Bay.
It wouldnt bother me if I didnt know your reputation. Id take a punt for a few bucks.
How much did you think you were gonna ask for your marks?
It all comes down to price and perceived value.
As long as it is just a hobby, and you dont expect to make hundreds of dollars.