Great info
graraps 
We are planning to visit Venezuela in the next week or two, flying in from EZE.
I've been on vacation to way over 100 countries and have seen these sort of things many times.
However we are in a bind, as I want to book in ADVANCE a 5 or 6 day plan to save hassles. A few days in Canaima, and a few in Las Rochas, and sadly I'll get screwed up front at real exchange rate. (Unless I can pay them in cash on arrival with Bols I get myself?)
Short of knowing a travel agent there I can't see a way around that.
I am pretty street savvy so will be looking to swap a few $US100 or so at the airport or somewhere that appears fairly safe.
So 5 to 1 should be pretty easily doable with no real contacts? What always worries me when arriving is getting old out of date currency that gets palmed off on tourists!
I carry around a few of these babies in my wallet I got earlier this year .. now THAT is a currency with issues!