Hello Necrosoft
From the description of what you provided, I see nothing wrong with what you are doing. Buying items with a level 1 alt from a vendor is not breaking any rules, nor is auctioning those items.
As long as you don't use any outside program or multibox to escort yourself to the vendor, I don't see any problems.
If you would like any further clarification, feel free to ask or PM me.
-Witcher