Thanks for your answer.
But one question, if you have 2 databases, how to mix the ads from both?
Still, I guess I'll have to do something like like that. Ads would be free or non-free, but I would only grant access to free ads to those who have paid me 99 dollars, cancelling their access after one year. Some manual work...
But how to prevent those dealers that I want to pay from posting free ads? I need differents user levels. On a phpBB forum, you can set different user rights, like user and moderator , could it do it?
Let me imagine:
To post an ad, one has to register. Once registered, one has 2 choices. To post one ad, then it's 2 dollars, he pays and here he goes. But if one wants to post several ads, it's 99 dollars. One pays, and one gets a page telling that his request is being processed. Time for me to get an e-mail from Paypal, seeing the payment, and then I would have to elevate that new member to the moderator status, where he can post as many ads as he want, until I remove him that right, one year after.
Ther's got to be a way...