Dec 27th - 30th is coming out more expensive than buying MQMs directly for everything I've checked so far. The best I'm seeing for an alternate date so far is:
Sun Dec 16 LAX-MEM-MCI-MEM-LAX
Nets 4,012 miles for $302.20 (7.5¢ per MQM), departing on the red-eye at 1:35am for MEM
To buy 2,500 MQM directly from Delta for $395:
https://dn.delta.com/skymiles/purchasemqms/buy/landing