The simplest way would be to get the Charming Imp and just set him to eat all the charms then you can just loot all.
But I have to say summoning is by no means just a money sink, it is a bit of a money sink to train sure but loads of familiars are extremely useful in pretty much every other part of the game.
Nearly every non-combat skill has a familiar that's useful in xp rates simply because of invisible level boosts or a passive affect - like the granite lobster for fishing, lava titan for mining, nightmare muspah for divination and arctic bear for hunting.
Then you have your combat ones that help bolster DPS in combat scenarios to improve xp rates and the amount of loot you are getting - such as the steel titan and nihils.
Then you have beasts of burden that help in almost any situation by letting you bring more supplies or carry more loot to prolong a trip - such as the pak yak.