Those that have been edited, reprinted in facsimiles, or transferred to microfilm can be borrowed through E Z Borrow or interlibrary loan if they are not in Tripod. Many of them will be listed in WorldCat under subject terms and the word "sources." For example, the search 'inquisition spain history sources' produces results including:
Tribunal de Toledo, causas de fe
Inquisition trial proceedings on 13 rolls of microfilm
Books printed in the 16th or 17th century are kept in libraries' rare book collections. You can go to Bryn Mawr, the University of Pennsylvania, and other local libraries to see these books.
For visual evidence, popular prints are a good source:
This study includes 133 full page prints along with short commentaries.