Merit buying is just stupid, why would anyone risk his account at a cost of getting red trusted or even banned?
Its abuse of the system as well and hence it is tagged if found and proven guilty.
I can see only one reason to risk your hard earned cash and precious (if Full Member and above) account.
Why do you consider your account so precious? Having an account here does not make you eligible for anything in general - what you apply for is a different issue. Having an account and having economic thoughts about the account shows your willingness to use the account solely for spamming your signature and not joining the discussions. If you do both properly then it wont be an issue.
The seller should write you a cool article, which would be very useful for the community.

Then nobody will question your merits, assuming it is not a plagiarism (ouch). Oh, I just created a new job, a merit copywriter.
I like your style mate. But truely speaking we need some sort of regulation on the merit system now.