Understanding all the ins and outs of
DVC can be overwhelming, but the best thing to do is to read and ask questions!
The number of points needed for your stay depends on more than just room type. Resort and time of year play a role in how many points are needed. Weeknights are less points than weekends. For example, a week in a 1-bedroom at SSR can range from around 185 in Adventure season all the way up to 316 in Magic Season (summer).
If your plans are to go every other year, you would only need 1/2 as many points as you could take advantage of banking your points every other year.
Right now, you have the option of buying directly through Disney or through resale. If you have a preference for home resort, then most will tell you buy where you want to stay. If you are not that concerned about where to stay, then looking for a resale contract that gives you a lot of points for less cost may be an option for you.
The cost per point through Disney is $112.00 for BLT, SSR, and AKL. If you buy in at the minimum, 160, you will save $5.00 per point (BLT) and $6.25 (SSR and AKL). There are also incentives to go along with it. It puts your initial investment at around $17, 000 - $18,000. However, through resale, you can get contracts right now at SSR (which doesn't expire until 2054) between $70 - $75.00 per point. And, when buying through resale, there is no minumum # of points to buy.
Since you are used to staying at POP, the cost of DVC is going to be more than you are typically used to spending. However, if you are thinking long term, for 1 - 2 bedrooms, then it can be a great value!
Good luck!