I had a similar experience with my BBS. We did UUCP with some rather remote nodes and I had 11 incoming lines (the maximum BellSouth would install in a residence) so the bills were not trivial. Each month I’d post the prior month’s bill total and small checks and envelopes of cash would show up in my post office box soon after. It never made a wild profit, but there were only a couple of months where we couldn’t cover the bills.