Lynne - I, too, am trying to figure out if buying DVC is wise for us. We've rented a few times and are just still mulling it over. You sound very well educated and I'd LOVE your input on how this was a smart financial decision for you? At first I said "NO WAY," but I just ran the numbers on 125 pts at Poly and it if we plan to go every 2 years then it seems like it's not too bad and actually cheaper than just booking a stay at the Poly. But if we just continue to rent it's about the same. I'd love your input! I'm not a financially savvy person.
There's absolutely an emotional side to owning DVC, but if you want to get a handle on financial side, the math isn't too complicated.
To make it easy, let's say you buy resale for $80/pt. Let's say maintenance fees on those points are $7/pt initially. When finding a comparable benefit, you need to look at the best deal, which is almost always renting points. Let's say, conservatively, it costs $15/pt to rent 11 months out. Accordingly, each year (assuming you go once/year) you are saving $8/pt (the $15 alternative minus the $7 MF cost). Since you paid $80 upfront, that $8/year savings will pay you back in 10 years (assuming you go once/year).
This benefit changes if you don't go every year, but it's important to not forget maintenance fees. This example is simple and easy, especially since you can assume that the cost of point rental will likely track with maintenance fees (so you don't need to worry about inflation).
This example ignores the time value of money - which really only matters if you think you could invest that money successfully earning 3-6%.
The reality is, holding a contract to the end of its life, assuming you go resale is probably going to be equivalent to an 8% rate of return investment. Not bad, but you need to use it effectively.
Point being, resale can be an OK investment if you'd definitely go otherwise. Direct from Disney will be a lot closer to a wash since you're paying 50-100% more up front - this extends your payback and lowers your rate of return a lot closer to zero.
If you buy from Disney, you're paying for the incidentals that can be taken away at any time, but you get the emotional gratification of being an "official" DVC member. To some people, that carries value on its own - just know it will take quite a bit longer to "make your money back".
Hopefully this helps!