We bought a 100 point resale at BWV.
If you want to travel in studios during adventure season, i100 pts really is more than enough.
However, we've found that the more we go...the more we want to go. We bought APs on our last trip and are now considering an add on at BLT.
Also, make sure you find a UY just prior to when you wish to visit. It would also be great if you had some flexibility in your job schedule.
With 25 points, you could easily lose 2 years worth of points because you planned a trip with banked points late in your use year and then had a family emergency.
I really think 50 points is a good amount of points to get your feet wet.
As for resales -- you can buy fewer points, and for less money per point. It takes longer (2 months) than from Disney and you have to deal with ROFR.
ROFR - Disney has Right Of First Refusal. This means that any resale deal has to be sent through Disney for their approval. If the deal is too good to be true, Disney may choose to buy the points from the seller.
Disney has not ROFR'd a lot lately due to the bad economy, but if you found a seller willing to part with SSR points for $50/pt. then you might get ROFR'd.
The sponsor of the
DVC DIS boards are reputable. We used DVCbyresale.com and was very happy. There are others as well.
If you want your points immediately, want to purchase BLT, need easy financing, or feel more comfortable purchasing from the mouse than a faceless online company, then straight from Disney is for you. Of course, the minimum is 160 points.