One of the more difficult aspects of presenting your ideas is that of hard evidence of your target market (the people who will buy your product and/or service. This part of the process takes effort. To help you get started, below are some sources to learn about size of a market and trends. For the presentation to the Sharks, you do not need to get to deep into the data unless you want to. BUT of course, the pitch with good, convincing data has a stronger chance of winning.
NAICS Code (North American Industry Classification System)
Find NAICS through the US Census wiebsite or place into your browser (http://www.census.gov/cgi-bin/sssd/naics/naicsrch)
or
Find NAICS within the NAICS website or place into your browser (http://www.naics.com/search/)
Once you have your NAICS code, you can do some Google searches. Of course, you will need to be creative in the way you word your search.. Try different ways of using the code or the name of the industry.