It is perfectly acceptable to charge a fee. Make sure you have this fee in your schedule of fees and charges used for disclosure. If so, call the attorney who subpoened the records and tell him its X bucks per hour, so much per copy, and when you have the records they can come down with a check and pick them up.
You can also submit a bill to the court.
Unfortunately, in many cases the parties are not speaking to each other and the party requesting records, is not the one in posession of the old bank statements and cancelled checks.