Honestly signature campaign would be good for you but with that limited budget it means your project might a get very limited exposure over a short period.

Even add banners might be a little more expensive for you since the ad spots are usually taken up through auctioning where bidders can sometimes go as high as 0.1 BTC and that only for a week.

The choice  you have now is to first create a good ANN thread then maybe with time you can try to organize a signature campaign. One step at a time.