Many public libraries offer interlibrary loan services for free or low cost to their library card holders -- they will borrow a book or journal article from another library and make it available for you to check out at their branch. To locate a public library near you, visit Libweb.
If you need more than a book or article, you can also contact a company to have research provided for you. The New York Public Library's Express service offers fee-based document delivery and research services. You may also want to check with your public library to find out about local companies providing these types of services - referred to as information brokers.