Sorry this deal has expired!
Priceline.com seems to have taken down the ability to book those fares as of noon Pacific Time. Book on flightnetwork.com instead!
As posted yesterday, Delta Skymiles MAY refuse to issue miles booked on priceline.com (I do not think so though). They will not do that with flightnetwork.com.
I'm not sure if they have a 24 hour free cancellation policy (it does not look like it).
Also the company bills in CAD so use a credit card without a foreign exchange fee!
I will keep searching for other sites. At this rate this deal will be alive for weeks!