The number of crackers in existence is going to be hundreds or thousands, but that is including crackers on old inactive accounts that will never be logged into again.
Then you have to consider how many crackers are on active accounts, but will never be put back into circulation due to these people buying one to complete their rare set.
Lastly, you have to consider how many are actively traded. This is the only number you can come close to guessing on. The number is very low because crackers are rarely traded.
~Efficiency Experts member
~5.8b XP