As others have said, no it isn't possible and for very good reason too.
To sell here at BHW you need to show a certain level of commitment to the forum and its members. From those 100 posts others can tell a lot about you by the content of the posts. If you post 100 short and useless posts it says something different about you than it does about the member who contributed 100 posts that helped others and actually contributed something useful to the forum.
Then there is the financial commitment too. Are you willing to hand over $97 to assist towards the financial upkeep of the forum?
Although these two things won't stop someone who is determined to use the forum with the intention of selling crap services/products to members at least they allow the members to form a more complete picture of the type of person you are before they hand you their money.