[22c]

It gets more interesting if you optimise for time instead of cost. If it takes you 15 minutes to craft something using 80c of currency, but you can instead run maps and average 300c an hour, then you still might prefer paying 100c for the guaranteed outcome (buying it already made) than going for "average" cost of 80c and having to craft it yourself.

Do it again, but optimise for fun instead of time and we've come full-circle :)