Its a grey zone when it comes to "homebrew" projects as we've allowed them to exist in the past (and current).
As chinny22 said, VOGONS is no marketplace. So you cannot handle the sales process directly here on VOGONS. Most other projects, like Serda's have an external website to do that (I've seen Google Forms and email also being used).
If you open a thread and present it as a project that will be fine even if you if say where to acquire it. What differs here is that you've already made the product while others make the threads when they start the design phase to get input and feedback from other users. Its imperative you don't just present it as a sale advertisement, but include more information regarding the creation/design process so other users can take some participation.
This is subject to change at any notice if the mod team decide to set better guidelines on homebrew projects.