The more I research the "olde" Maine, the more I realize how many areas of the coast are quieter and less populated today, both on land and on the water.
5 bucks seems high until you figure how big Rockland Harbor is, if they'll pick you up anywhere and deliver you to several points. RYC likely is trying to cover it's costs of boat and operator.
Last I knew, in Camden it was 2 or 3 bucks. Nantucket, last we were there was very high I recall. I like to row but it's nice to have a launch if we have guests coming.
I think Northeast Harbors new launch is free with a mooring. Those 3 mentioned are the only launches I can think of in this vicinity.