Nice to see a manga where the MC isn't a pussy foot loser that doesn't aggressively go after the girl he wants. Probably because the artist has experience drawing hentai, and isn't sexually repressed.
Palmasque is certainly very interesting social situation in that it appears to be an autonomous democracy of sorts but then it restricts the freedoms of its citizens/craftsmen from leaving the island. I guess the punishment would be for attempting to leave, because once the craftsman has left...
In the Light Novel Sherry talks them down to 20 silver per mirror... And it's not really discussed anywhere, but the 1 silver coin entrance fee is probably used to make the palmasque mirror, which requires silver to reflect. Keep in mind that palmasque doesn't have a nearby labyrinth, so there...
I agree that the price of the mirrors changed over the course of the Light Novel as Sherry negotiated with the Mirror Shop Owners Wife to eventually get the price down from the 55 and 35 silver priced mirrors down to 20 silver each, BUT they didn't buy them ALL in advance. From what I remember...
Looks like the Manga took out the discussion with Laurel about how the skills of Sex Maniac worked. Probably okay, really had nothing to do with the plot, just fleshing out the background.