You are not aloud to directly sell the pins to the customers. That's why there is something called upgrade services. You are suppose to apply the pin to their account yourself. After buyer pays you you are responsible to upgrade their account right at the time of transaction.
Its basically the same thing. If they ask to "buy all pins" they mean that they would like an upgrade on possibly multiple accounts or all on the same account. Any direct pin sell isn't aloud on Sythe.
Let me clear this up.
We had a legal issue with the word "pins" floating around here on Sythe.
Upgrades are the alternative. We're doing it as a service but not trading the codes themselves, which was the issue.
I hope this cleared the issue up for you.