You can always buy a report, sometimes it is worth it, other times it may not be. I've purchased a few lists/resources before and wish I would have done it sooner. Sometimes the report can come from a trade group.
Here's my quick suggestions:
- Use Facebook if it is a consumer group to create a mock ad for the target demographic. Do geographic searches based upon the likes & interests that you can add and remove for a segment of the ad viewing. Pay attention to the right hand side of the screen and you'll see the total number of targeted users change as you add criteria. This is more accurate than census data.
- Use http://news.google.com to find the trade/industry terms, frequently the reporters will quote industry trade groups or basic information of the industry that they have been told or they have researched. If more than a few people specify the demographics try to verify it and take it as a good sign.
At the end of the day it is how much effort you want to spend. If you have a week to gather the info, scout out the news articles & trade press releases; otherwise just buckle down and buy the industry report, but contact the report company before and ask if the information you seek is in the document. There aren't refunds for those items typically.