It's easy to get merit without having to buy, just by being a good member and following discussions and giving good and quality feedback. other members will appreciate the comments and posts you make.
People need merits to go up in ranking and participate in signature campaigns that pay good return. There isn't any good bounty for Newbies, Jr or Member rank. Getting merit is not hard but it takes time and effort. Just see this thread for instance, OP got 7 merits for starting this thread. One can get idea by reading such posts that how to get merit.
If you buy high level account then chances are you will very soon get red flag for violating rules, that will make your account and investment worthless.