Come on George, the cost of the warranty is ALWAYS paid for by the consumer. Whether it be as an extended warranty itemized in the sale of the spa, or as a "hidden" cost not itemized in the overall price of the spa.
If comparing 2 exact same spas, one $5000 with a 5 year warranty, and one $4000 plus $500 for a 5 year extended warranty........... well
An extended warranty is simply a way of lowing the initial price of the spa, and offering the consumer a choice of whether or not they want to spend the extra $ or take the risk.
Some will always take the insurance (piece of mind has value for many), others understand that insurance is a profitable business and the payout's average less than the premium (usually :-)