You will have to set up a proper app marketing strategy.
One major part of this app marketing strategy should be App Store Optimization. It allows you to efficiently push your organic app downloads and visibility within app stores.
An important step in ASO is Keyword [url removed, login to view] goal is to reach 1 million installs with less investments. Our app is a social networking app named 'eGoo'. One of the main objectives is the Optimizing process . These kind of strategies don't actually need investments.
Please bid if only you are willing to bid under the budget :)