The economics of wallets, purses, etc.

I saw a post from a couple years ago advising to open billfolds, zip wallets and coin purses. I've been doing that but I never find more than a driver's license, a little cash and on occassion some drugs. Balance that with the fact that billfolds are worth $40k, zip wallets are $8k and purses are $4k, I don't see the advantage to opening. Can anyone explain?