The resources below provide transcripts or recordings of arguments before multiple federal and state courts:
The California Supreme Court has recently begun posting its oral arguments for free:
Most federal courts post any available transcripts and audio to PACER, where they can be retrieved like any other court documents using Bloomberg (if you are a law student or faculty member) or an individual PACER account (if you are not.) Try searching the docket for the keyword transcript or transcripts to locate them.
However, keep in mind the following restrictions:
Fortunately, a few courts have begun making transcripts and recordings more widely available on their websites. Try these starting points: