Are we allowed to trade between characters by setting up a bazaar with a password on main character and buying items on the cheap with another character on the same account or is it against the rules?

Yes, you just have to bug your stall.
To do so, the second you go through any portal, Alt F4 right away. However, it may fail at some times.

Is that allowed or against the rules?

Winter de Solis wrote:Is that allowed or against the rules?

Well, CS hasn't tried to do anything about it, so not really against the rules.

.