Can anyone roughly tell me how much 250 points costs?
Is this enough for 2 weeks at say SSR every other year?
How much is the annual fee?
Can you bank points for ever, or do they only carry over for one year?
Just to elaborate on some of Claire's points:
The price per point is for your annual allocation of points, so a one-off payment now of, (to use round figures) $10,400 for 100 SSR points would be buying you 100 SSR points
every year until the end of the contract in 2057(? not sure of the exact year!)
The annual maintenance charge can go up each year (or down), and does vary somewhat depending on your home resort. There are, however, strict parameters for any charges / increases.
You can make a banking transaction every year 'for ever' (until the end of the contract anyway

), but each transaction carries the banked points over for only one year. So you could, for example bank 50 points every year and the effect would be the same as banking your first lot of 50 points 'for ever', but would, in fact be a different set of 50 points from each year carrying forward to the next year.
