RM2 had only a loose connection between its item creation rules, item costs, and what items it included in its treasure lists (a good part of C&T's non-basic magic items were translated over from another system). RMSS's Treasure Companion did a better job of bringing things together, but even in RMU, I had to leave the really non-standard stuff like "gains an extra +15 OB when used under a full moon" effects with some general guidelines.
For things that substitute for mundane services, I'd probably want to price them about two to three times what it costs to just have someone do it. There are advantages to doing it by magic, but the market isn't likely to bear much markup, unless it's a truly paranoid society where every barber is seen as a cutthroat and every housekeeper a burglar.