Buy VB or HHI if you want to stay there. Don't buy it to stay at WDW. As DVC builds more DVC resorts at WDW, the competition for villas at seven months get harder. If you really want to stay at WDW, buy SSR or OKW. Dues are the highest at VB and HHI.
Some one on another thread posted that now at seven months out there aren't any studios left at the Polynesian Villas and Bungalows.
You can bank from a previous year or borrow from your following year's points. You can also purchase one-time use points from Disney, but they are pricey. If you absolutely don't want to bank or borrow, you can always rent or transfer from another member.
First you need to work on your math. Then you need to look at the maintenance fees for Vero Beach and Hilton Head. The recurring costs will eat up any initial savings very quickly.