it's same actually Old Newbie or Brand New, it's just to create an illusion that the user has been with bitcointalk.org for a long time so user can be trusted. Just my opinion.
If I'm not wrong Avatar is allowed based on member grade not based on how old is your account. In order to have avatar in your account you must be at least Full Member otherwise it is not allowed.
Intrested? Send me your price please...
Literally there is no use of these old newbie accounts. If your thinking by using old new accounts any one can increase their posts accounts without any 2 weeks waiting time then your completely wrong. In order to remove that two weeks waiting time limitation you must have either visited or posted at least one post on each account for every two weeks from the date you created these accounts.
I strongly believe you didn't do for those 50 accounts so you old accounts are as good a new accounts their is no value for those accounts. Please do not buy these accounts