Waitaminute.. He just:
1) Split the party.
2) Got rid of a level 4 equivalent (that is, 4 hit dice) cleric-grade melee combatant.
As background, Fighters are better than Clerics, which are themselves better than Mages. Also note that our MC is only level 2.
3) Outright deceived his companion.
4) Never confirmed that he'd be able to buy her back for what he received / confirmed she wouldn't be chopped up for meat / sold to someone else / sacrificed to a greater tentacle god / etc.
Four) Got Rosinante's gender entirely wrong despite having the book.
If I were his DM, I'd be laughing evilly (yet secretly and silently) behind my Dungeon Master's screen, right about now. ^w^
Thanks kindly for the great job Mediocre Scans team!