If you are subscribing to one of the fee-based sites for one particular database, find out if it is available elsewhere online. Another site may have the same database online at no charge or have images posted without an index. It can vary from one dataset to another.
I’ve subscribed to fee-based sites because they had one set of records that interested me, usually on a short term basis. Just make certain that there aren’t other ways to get at the same information.
Sometimes those free sites will have the same set of records but won’t have a complete index. Find out beforehand.