I've seldom seen a station sale (particularly in a smaller market) where cash accounts owned by the seller were given to the buyer. If accounts with cash in them are transferred to the buyer, that amount is added to the sale price at closing. There is no "free money".
At closing, generally the new owner has an agreement where they handle accounts receivable and give that previously earned money to the seller less a small percentage for handling receivables. That's the only case where funds are "intermingled".
Separate agreements will exist on prepaid expenses, like property taxes and prepaid rent. If a seller has paid a business license for the year and the sale closes in June, either the license was considered part of the deal or, at closing, the buyer reimburses for the paid portion they are getting.
From that point on the buyer will use accounts set up in advance for things like payroll and expenses.