Anything digital you want to buy can be found in the Digital goods section (Accounts/invites sub section for your case). It's not against the rules but it's never recommended to buy an account, It's better to make your own and deserve the rank. If you buy a high quality account for instance and you start posting low quality posts, people may notice and you may end up having a red trust which will make your account worthless and you will no longer be able to join signature campaigns.
Thank you for your answer. I'll read section about Digital goods. I agree with you about buying. And I'm developing my own account now. It was only a question because I try to develop in different ways.
