It really depends on your information needs.

At larger institutions, if you are faculty, a graduate student, or even a high achieving undergraduate, you can get funding to travel pretty easily. At midsize schools or wealthy small schools, it about the same but a little more difficult for undergraduates. At small schools, faculty and graduate students can get some funding but not as much as they’d probably like. You can also get grants from professional organizations, interest groups, the federal government, and other places I’m surely forgetting.

If travel is out of the question, archives usually provide a set amount of time to do research for you and then will do research beyond that, for a price. I believe research and special collections libraries operate the same way. You can get grants to help cover these costs.

Another option is to use the internet. More and more resources are being made available digitally everyday. There are limitations to this obviously but you can get a decent amount of information if you know where to go and what to look for within your area of expertise. And if you don’t know where to go, start with a librarian. They’ll either know where to go or know how to find where to go.