Add a fee to post Ann thread. Restrct Newbie accounts from posting Ann thread.
Make a paid bumping button, + free bump for every earned merit.
Any paid option will just mean money is leading the forum. Instead of restricting newbie account from posting ANN thread we can just remove the bump that is currently caused by newbie and Jr.Member.
A bump button , powered by Merit is good idea but that also need to be restricted for number of thread the user will be able to bump in a day (like max. 2 or 3 in a calendar day) because I suspect somebody start buying Merit and start providing bump facility to the ANN threads so even with Merit , you cannot bump all the threads on your wish.
Edit: Once we have taken out the bump power of newbies and Jr. member , then punishing the spam will also become easier, because you are now risking a temp bans on a higher ranked account if you caught spamming.