A liter of San Pellagrino ~ $2.59
A liter of O.J. ~ $2.99
A liter of I.D. coffee creamer $5.49
A liter of beer ~$6.10
A liter of cheap whiskey ~ $33.80
Fuel, that costs an enormous amount of money to find, extract, ship, refine, distribute, deliver and then pump into your pleasure boat, is still cheaper than bubbly water. You are competing in a global market with the semi-truckers, the farmers, the military, the airlines and Fed Ex. There is limited capacity and those guys need it 'way more than you do.
When I cannot or choose not to afford the cost of anything else, I quit buying it. If that happens often enough, the price may drop - Economics 101. Some of those major buyers that you compete with will pay $2.50, $5.00 or $10.00 per liter. High bidders get the goods. Yet some boaters still whine about fuel prices 'cause they will never grasp this reality. Consider a different hobby. I'll be boating all summer.