I think you can even reduce that amount to 5 for the major forums and infinite for the off-topic and other geeky stuff subforum. Then after the 20th post maybe increase the limit to 10.
I doubt many users have such a huge amount of knowledge about mechanical keyboards when they first join the forums. And even if they have it, the other users sure can help out as well or the new user can post it the next day. I personally am a new user too, and of course I want to get active in the classifieds section but still I feel no need to spam every board I visit, instead I try to help here and there to get to the 60 posts slowly but steadily. Then I see other users, like a certain instrument, posting in every second thread that interests me and it really annoys me, then I also see that he also has a link to an offer of him on eBay (that's something I would not allow as well). Have some patience, if you want to sell stuff put it on eBay, people who search for it will see it.