@GambierBay tbh, that's somewhat debatable. So far, the money amounts listed have been (from low to high):
(ch3 pg11) A drink - costs 300
(ch4 pg1) honey soda - costs 330
(ch4 pg1) sausages - costs 980
(ch4 pg4) quest: kill a slime - gain 1,000
(ch5 pg6) 1 night an the inn - costs 2,500
(ch3 pg14) mercenaries/adventurer hiring - costs 8,000 each
(ch3 pg6) "defeat a bunch of monsters" - gain 10k
(ch5 pg12) camping kit - costs 45,000
(ch5 pg13-14) quest: find fancy golden drug flower - gain 100k
(ch4 pg3) quest: find people willing to sell their kidneys - gain 500k
(ch4 pg3) quest: kill a dragon that's eaten 50 people - gain 1m
(ch3 pg4 & 6) Luxury ship to demon king's castle - costs 500 mil
Assuming this is using the yen system (1 being the lowest instead of 0.01) then in dollar values it'd be something like $10 for killing a slime and $25 per night at the inn.
IMO, the main problem is they're not doing much to gain money. Most of it came from the hero "defeating a bunch of monsters" one time and they haven't really done much except kill a single slime since.