~ Buying merits is against the rules, ~
Is it? I know it is frowned upon by legit members but I haven't seen anyone getting banned for buying or selling merits. NeuroticFish already posted a thread for reference. There were also cases were merits sent were rolled back by admin but I can't remember if that was related to merit trading.
@OP, your best option really is buying a copper membership. The cost could be higher at first but it's only a one time payment to enable you to post without the newbie restrictions and you also have full control of the thread. It's cheaper in the long run compared to buying the services of higher rank members and buying merits.
When it comes to account trust, you will be able to build that also if your project is legit and if you are serious in building it.