Hire writers and have it publish to reputable public relations website or any news website. It's true that marketing really is bringing in the most for a project.
But, it doesn't have to be all marketing and you still have to balance things or still focused in the development of the project. It's like that you're all buzz but no good content if you'll focus in marketing.
divide in both them is the best option for the success. If you keep that in mind that marketing alone will give you success then it will not if you do not have beneficial product or if you do not complete the product for which you invite the people. Product alone also do not work in many cases. Your marketing just bring the people to see that what you have for them and after seeing that they decide to stay with you only if you have further potential to give them a great product or benefit.
both are vital in the success of the product to the market. product itself and marketing. if the op has already good product to offer to the community, good in the sense that it is not in the alpha or beta stage, but fully functional one, then, this is the stage where it is good to promote your product. because if you will spend like for example paying a writer or blogger about your product and you're not ready, then it is just futile to do so.
would be worth paying for marketing activity if you have readily-available product to the market because if potential customers will inquire about it, you are not in a hurry to address some possible issues upon trying your product.