I will be adding to my Modern stock pile to play all types of fun decks; during this month because I have a lot of cards I am in the process of redeeming, and also in the long-term.
Here is $10 to the bots (October 8 and 9, 2013), especially to help my UR Delver, WG lifegain and monogreen decks.
Next, for $2, I added the more affordable artifacts from Modern Masters (October 12, 2013). This is my current stash including the cards I pulled from packs back when they were available.
Oct 15, 2013: $5 to the bots to have 3 or 4 of every common card in Modern Masters.
Also during the October 15, 2013 buying day: Adaptive Automaton from M12 and Doubling Season (both for $6.14)
I added some imprint and entwine cards....these cost me $15.
October 26, 2013: $10 to the bots to get all of the cheaper uncommons (and that's almost all of them), and a few rares.