Not that expensive, there were 4 of us, drove up stayed at a nice Holiday Inn near the water, two days fishing including tip for first mate, total cost was $350. breakfast included at hotel so we just bought lunch and dinner or one day just one meal because we ate a little later and were full.
I went on a small charter out of Maine a few years ago, there were 3 of us on the boat fishing and the captain did just that, we caught mackerel then caught some nice stripers, no 40-50 lbs but some nice one's nonetheless.