The full text of more recent reports are on the GPO FDsys and THOMAS websites:
GPO FDsys provides the full text of committee and conference reports from the 104th Congress (1995-1996) to the current Congress. You can browse a chronological list of reports, or use the Advanced Search to search by a variety of fields. Highlight "Committee Reports" in the Available Collections drop down box and add it to "Selected Collections".
Starting with the 111th Congress (2009-2010), GPO also began publishing conference reports on a separate webpage.
THOMAS provides the full text of committee and conference reports from the 104th Congress (1995-96) to the current Congress. Although you will be linking to the full text of the report on FDsys, the THOMAS page can be easier to search.
The Senate and House Document Rooms may be able to provide you with a copy of a committee or conference report. Check with them for availability.
Committee and conference reports may be available in large library systems or college libraries, frequently as a part of their participation in the Federal Depository Library Program (FDLP). Over 1,100 libraries participate in the FDLP, collecting and/or providing public access to government documents. A list of depository libraries is available on GPO's website. Since most depository libraries are within a university or state library, calling ahead to ask about hours is advised.
Purchasing from GPO
Congressional reports may be available for sale from GPO; you will need to check GPO's Catalog of U.S. Government Publications. More information is available from GPO by calling 202-512-1800 or 1-866-512-1800 or by visiting the online U.S. Government Bookstore. You may also fax or mail an order form.
All conference reports are printed in the Congressional Record three calendar days before floor consideration, unless this requirement is waived by unanimous consent or by a special rule.