Healing Potion Deposit
'You can buy supplies from the outpost at 25% above normal market cost.'
'Neat. I'll buy some studded leather armour with my new-found wealth. Can I sell them my old armour?'
'Yep, at 50% below market values.'
'Right-o. Hmm, can I sell them my old potions of healing?'
'I suppose so, but it doesn't sound like good financial sense.'
'I don't think you're getting my meaning.'
'Oh, you mean a used potion.'
'Now you're getting it.'
'Like the empty bottle.'
'Yep, like a deposit on a bottle of pop.'
'Okay, sure, they'll give you a copper piece for each returned bottle. It won't add up to much.'
'Au contraire, judging by our adventures so far, we'll soon be rich!'