is advertising random products allowed here ?
I don't know if you have noticed, but there is an ad banner that shows sometimes after the first post in a page. Those are official, i think you should be contacting the forum administration for this. This question would be better done in the
Meta area i think, not in offtopic.
I don't know the exact details, but I'm sure you can make a deal for it.
But if you just meant posting a message as an ad, i don't think so. Again ask in Meta for details.
You can offer your own services in the
services area though.