I don't really care for resurrecting people in game. I would allow it if the characters are working for a church, or if one of them is a high level cleric. Other than that, I think it should be reserved for either church figures or kings and dukes (and similarly powerful authorities). By allowing any old adventurer to get resurrected, especially if he was looting a tomb or old dungeon, really cheapens the spell for me. Resurrection should be earned, not just given out for a few thousand gold pieces.
While I can see various churches happily resurrecting people for monetary donations, I think I would have the gods refuse to grant the spell if it was abused, even once. If the dead person was devout, and actively opposing some major force of evil, resurrection would be granted with no reservations. If a cleric just goes and resurrects Ragnar the fighter, who has never worshiped at the church at all, because his buddies give the priest a chest of gems, I think the god just might cut off spells to the priest and force him to make atonement in some way.