[mjevans]

Probably a flat minimum. In the US I'd imagine it'd best be a log curve starting with a minimum of "minimum wage (of an hour)" and then shifting to a % of the cash inside. Something like a gentle decay curve where every base 10 increase there's a halving of the percent cut.

[dmix]

$20-50 seems like a fine reward for the average person. I’d probably give whatever money was in the wallet to them.