If your answer to that question is very much, as in "never enough" then you should purchase as many points as possible. Also, BUY RESALE! I paid $53 a point last year through The Time Share Store. Why pay $75 a point now for EXACTLY the same thing? (Unless you feel compelled to buy at The Wilderness Lodge Villas. I own at Old Key West, but have not stayed there yet. My wife and I have, on our DVC points, stayed at the Yacht and Beach Club, the Grand Californian in Anaheim, and will be staying at OKW for a week in July, and VWL for a week in September. It really can't get better than that! We bought a 460 point contract.)
The least expensive way to get two full weeks a year at WDW is, as suggested above, to stay at Old Key West during January, September, or the first half of December. That requires only 160 points. You'll need at least 10 grand to take the plunge, but always remember that you'll save many times that in the long run as long as you want to go there for the next 42 years.