I'm around your age, and I made my purchase last year. I purchased AKV resale without financing. I want to clarify some of what I see here and also give you my opinion...
First off, if you purchase through Disney by the fall you ARE NOT getting any extra points. You are simply getting points that you are entitled to because of the use year. Disney makes the words sound nice to make it seem like you are getting a great incentive, but you are only getting exactly what you are entitled to. For example, if you were to purchase points with an October use year today you are entitled to your 2011 use year worth of points since the October deadline hasn't come yet. If you try to purchase an April use year now, they will first push you very hard to something later in the year and then tell you that they can't give you the points. The only thing that Disney sometimes does here is extend your banking deadline. Since those October points had to be banked by May 31st Disney can be nice and still allow you to bank them so you have more time to use them. So just be careful that you aren't getting lost in the sales wording because Disney is just giving you exactly what you are entitled to.
Now...on to purchasing. As I said earlier, I bought 200 pts resale and paid in cash. I probably wouldn't have done it if I had to finance, but that is just my opinion. I highly recommend looking at the resale market, unless you absolutely want the ability to transfer your points for cruises and the like. These exchanges are usually a bad use of points, but some people still like having the ability. You can really save a ton of money by purchasing resale over direct, and probably get more points. With just a quick glimpse over at the timeshare store, points at AKV are going in the low 70's and Saratoga can be had in the low 60's per point. This is opposed to over 110 a point with Disney's best incentives and comes out to a considerable amount of money.
Your other financial consideration is going to be your dues. These will vary depending on your resort and usually increase a little bit each year (but usually less than resort rooms). This year my dues were 5.01 a point at AKV, and with a quick search you can see what they were at all the resorts. You get an itemized budget report each year though to see where your dues are going and how much in each area. You will be paying these every year for as long as you hold the contract.