When you buy a membership from Palace, you do get some number of free (referred to as "imperial weeks") and incentive weeks (where the AI rate paid when used is less than the full AI member rate) as part of the membership package. The number of weeks you get is related to the price you pay, and can be negotiated to some degree. I believe, though, the total value of the free/incentive weeks closely approximates the price paid.
The number of other weeks in the package, can vary wildly, and IMHO, is fairly meaningless. We paid $12K, and got 120 weeks in addition to a number of free and incentive weeks. We have yet to use a paid week, and are not likely to. When we purchased, we considered our contract payment as pre-paid vacations, more or less.