From a readers perspective, posting ads in forums is irritating. I look at the forums to get information and participate in discussions with people. When I want to shop for something I go to the buy and sell section. If every person who wanted to sell something put an ad in the forums, it would be quite challenging to navigate one's way around the ads. So, put your ad where it belongs, which you had already done, and use the forums the way they were designed to be used.