Incredibly enough, only with Theros is there a break-even pack price. All other sets are in the lottery realm, especially Nyx, or the Eidolon lottery.
September 3 update: Planeswalkers and the cheapest card for $15.
September 8 update: took out from list cards I bought, including Temple of Plenty, and cards I will not buy: M15 Garruk, and Goblin Rabblemaster.
September 10 update: took both Ajanis and the M15 Chandra off the list, and added Purphoros (a miss from before).
I would like to play the Scry lands in casual Modern.
Here are the Gods.
September 21 update: I am giving up on Master of Waves and Keranos.
September 26 update: time to complete the scry lands for future Just for Fun play.