banned after I reported it here
Correct. There are just too many sellers/threads in that section for moderators to be able to catch them all.
its the same person, because he keeps coming back with the same posts, after I report him and he gets banned
im certain he already has a new account
This is due to the current (and somewhat faulty) setup of Digital Goods section. Pretty much nothing prevents a scammer or spammer to come back very quickly.
It seems that he have many newbie account, that is why you need to exercise more caution when dealing with lower rank members
Either don't deal with them at all or use an escrow (although useless in cases of digital goods which can 'stop functioning' at any later time).
