Semi-related to which, here's a half-formed thought occasioned by the monster Yield mechanic of Hackmaster 4E and by the Egg Hunter campaign concept from Noism's epic Let's Read the Monstrous Compendium.*
Skin/gut/nest-rob a treasureless beastie: a party can garner 10 x lvl^2 gp per turn of gutting, up to a maximum gp value = its XP.
The form this treasure value takes is dependent upon the creature type (hide/fur, feathers/scales, organs/secretions, eggs/young, etc.), but usually has to be hauled back to town and converted to hard cash at a market.
Bigger, more dangerous creatures are worth more to interested purchasers (fur traders, tanners, haberdashers, corset-makers, wizards and what-not), but take longer to render down into sweet convertible value.
Why a value per turn? Coz more experienced adventurers are more practised in skinning and jointing beasties purely as a function of their experience as scavenging murderhobos. Pay a time penalty: derive extra loot.
And that is how you get value out of whales, beavers, owlbears, and similar loot-less beasties.
* On the subject of Let's Reads. Yes, LRM will be returning. I intend to finish it if it drives me mad.
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