The most important thing about cost-effective marketing is to focus on high-return activities. Different channels work for different companies, there's no one-size-fits-all. If there's one thing we know though it's that you should absolutely spend money on marketing your business online. Even a budget of $1,500 can go a long way.
The great thing about research is that the only resource you'll need to spend is your time. If you don't do thorough research before spending your first marketing dollar you probably won't put the remaining $1,499 to particularly good use.
A good place to start is by doing a quick Google search of your industry, identifying patterns, understanding consumer behaviour, studying your competition, and even reaching out to your target audience for first-hand market research. The data you collect during this process will serve as the foundation of your campaign.
Certainly, there are ways you can spend money on research. There are organizations that sell reports with seemingly critical information, as well as tools that'll pull data from around the web for your consideration. Services like Springwise and Trendwatching are great for this, but can be a bit pricey. There's more than enough free information out there to help get you off the ground.