First, foreign exchange is so short that the national parks and the hotels will only accept US dollars (USD):  USD20 for Vic Falls park; USD60 for a simple lodge.

On the streets there were signs that it is illegal to change money except at a licensed bureau d' change.  However, there were many young men offering to get a good rate.

Then when one finds a bureau d' change that actually has cash, the sign outside shows the official exchange rate:  Z56 to the USD.  When one hands over USD10,  they write out a receipt that says USD10 accepted to purchase Z560, just like the sign.  But, they hand you Z5000!  And they have no Z1000 bills, so you get a huge wad of cash.

With that cash, some things are quite reasonable, others seem cheap, but some seem to be based on the official rate. 

Jerry and enough Zim-Dollars to pay for breakfast.