Disney will sell any
DVC direct. They will focus on the new resorts -- Poly and CCV. That said, buy where you want to stay or are at least willing to stay. Do not buy direct for the "discounts," because you will spend thousands to save hundreds.
The current discount that has economic value that cannot be duplicated via a Disney Visa or other means is the Gold AP. It's a savings of ~$200 each. For a family of 6 at a single address, that's $1200 a year, assuming that an AP is of value to that family.
Having an AP assumes that multiple visits a year work out, so it's a large number of points. For an annual trip, unless it's a trip more than 10 days, it doesn't work out.
A week in the cheapest season in the cheapest 2BR DVC is 155 points (AKV Value). To book this requires that you own at AKV. Buying the minimum number of points for an annual trip (not recommended - if you can't get the Value you'd be pretty stuck) would be 160. You can get a good 160 point contract resale for $90/point or so. That's $14,400. Direct from Disney, that same contract is $165/point, for a cost of $26,400.
That's a $12,000 difference. Even if you could make the APs "worth it," you can only buy the Gold for people living in your home. You'd need to buy 6 a year for 10 years to be even in range of the difference, and that's not even mentioning that if you're only staying a week the AP won't be "worth it." To buy points for a stay of more than 10 days a year, you're piling into the expense to save the $1200/year and the math kills.
The dining discounts can largely be replicated with a Disney Visa. The merch discounts are hard to make add up, especially if you're going yearly (how much merch do you need every year?).
AKV is a somewhat extreme example, but the numbers don't work for a more common example either. Cheapest week in a BLT 2BR Lake View is 248 points. A 250 point contract from Disney will cost you $185/point. Resale, it's about $120/point. A $16k difference between the two is very hard to make up with the discounts, and it depends the valuation you put on "pixie dust." If you do put value on pixie dust, buying 50 points direct (which makes you discount-eligible) and 200 resale still saves you $13k or so, depending on the 200-point contract you buy. I'm seeing ranges there of $119-126.