Count me completely confused. You think a service with which you were previously unfamiliar is suddenly "absurd" and "highway robbery" because it's $10 more than a price you pulled from thin air.
"Hey, I want to fly to Hawaii in a Harrier jet."
"That'll be $5000."
"What???? I guestimated it to only cost me $3000! How do you look at yourself in the mirror, scoundrel?"
$20-25 is the going rate at any place in the US I know. It's mainly because of the relative "rarity" of the machine/procedure coupled with the what could be considered "expensive" nature of the niche, essentially supply vs. demand. You might be happy to know that several businesses actually provide the service free when you buy from them.
For what it's worth, off all the advice I've given on here over the years not once have I recommended someone to go out of their way to have the service done. Frankly, I find it unnecessary, if not a bit OCD, for someone to "need" to have the hem finished EXACTLY as it was originally. People incessantly regurgitate and recycle the pros of chainstitching, and to each their own, but $25+ isn't going to make my $300 jeans wear any better just as the type of hem my jeans have will not keep me up at night.
But to advocate the service on such cheap jeans to begin with makes as much sense as your imaginary price gouging.
tl;dr: Srsly, bro?