I ran your scenario and came up with slightly better numbers. This is all in constant dollars, no figuring for increase in hotel rates or the annual dues. An important question to consider before comparing: You say you are currently spending $5k per year. You are then comparing that scenario to your proposed DVC vacation schedule. The important question is, Will the DVC schedule cost approx $5k or is it more? 22 nights totalling $5,000 is only $227 per night and this includes tax. This seems a little low to me, considering 13 of those nights are in prime July season. Add in the fact that those 13 nights are in a 1 BR and that really skews the comparison. I'm guessing your average cash cost should be around $300 per night for the studio and $500 for the 1 BR in order to even it out. That is actually a $9,200 cash reservation cost equivillant of your DVC contract.
HOWEVER,
There is no reason anyone should spend $104 per point on SSR. Even DVC sells it for $96 (a "promotional" price). However, there are tons of resales available for around $85. Let's figure at $86 to be safe. That makes a total purchase price of $54,868. Annual dues on 638 points are somewhere around 2,690. Based on these figures, I show you would break even sometime in year 23.
However, if you had the $55k right now and instead invested it at a simple 5 or 6%, then calculating a net 4% return after taxes would give you $2,200 per year to use toward your hotel expenses, resulting in only needing to spend $2,800 per year. This then becomes the cheaper than DVC at year 50. By then you will have spent 140,000 in cash and the DVC ownership will have cost you $189,000. This is flawed however because in reality the $2,200 will always be $2,200 whereas the hotel expenses will of course keep going up with inflation.
Based on your numbers and your scenario, I'd say a DVC purchase is iffy, unless you are really in it for the long haul. If I had the cash, I would probably not buy DVC in this situation.
However, as I mentioned earlier I don't really think you have set up an equivilant comparison. Using a more realistic $9,200 cost per year, I show you would break even in year 9 which is close to when most of us break even. At year 50 the cost is DVC 189,000 vs. Cash $460,000

HOWEVER,
There is no reason anyone should spend $104 per point on SSR. Even DVC sells it for $96 (a "promotional" price). However, there are tons of resales available for around $85. Let's figure at $86 to be safe. That makes a total purchase price of $54,868. Annual dues on 638 points are somewhere around 2,690. Based on these figures, I show you would break even sometime in year 23.
However, if you had the $55k right now and instead invested it at a simple 5 or 6%, then calculating a net 4% return after taxes would give you $2,200 per year to use toward your hotel expenses, resulting in only needing to spend $2,800 per year. This then becomes the cheaper than DVC at year 50. By then you will have spent 140,000 in cash and the DVC ownership will have cost you $189,000. This is flawed however because in reality the $2,200 will always be $2,200 whereas the hotel expenses will of course keep going up with inflation.
Based on your numbers and your scenario, I'd say a DVC purchase is iffy, unless you are really in it for the long haul. If I had the cash, I would probably not buy DVC in this situation.
However, as I mentioned earlier I don't really think you have set up an equivilant comparison. Using a more realistic $9,200 cost per year, I show you would break even in year 9 which is close to when most of us break even. At year 50 the cost is DVC 189,000 vs. Cash $460,000



