I think the rate for a party boat is about $90 per person in PortA. I actually think that's a descent deal; and I don't think the prices have gone up much in the last 20 years. It costs me about $100 a trip to take my own bay boat out (including towing, gas, bait).
If they're less than that in Galveston, it's a great deal!. Probably has to do with property values, and the economics of doing business in PortA being higher.