I want to advertise a workshop clearance, but....

[Tasky]

Wow - that was pretty aggressive. Is that how I need to act if I want to gain the status of "Valued Contributor"...?
No problem - I consider myself well and truly told.

It was a little aggressive, yes... but most internet forums with a Buy/Sell section (and any other sections of considerable use) tend to enforce a minimum post count.
This is usually done to discourage people from just breezing in, demanding a service or free information and then Cucumbering off. The whole point of a forum is the community, and all people ask is that you join in a bit, especially as forums cost money to run and it's usually the members paying for it.

One of my computer forums requires 1000 posts and a minimum of 6 months membership.
The bike forum I'm on requires 50 posts, before you start asking for long, detailed posts and photos of how to fix your bike, instead of just buying a Haynes or paying a mechanic.