I've started playing again sporadically over the past couple of weeks, and really picked things up since the big Torotdrone update. In that time I've been pretty much everywhere: the daily Danger Missions, some random T2/3 cruising, a Treasure Vault or two, a Danger Room, hunting for Fiends in T1, a FSC run, you name it. Almost all of it has been on Elite difficulty too. In all that time, I haven't stumbled across a single Spark of Life. Not. a. one. And since the last few limited-time special events have mostly consisted of, "Throw out ALL the damage!", I've been absolutely bleeding Sparks. Seriously, I think I was in the mid-60s before Halloween rolled around, and after a particularly-gruesome Vanaduke fight today, I have all of 23 left. (Note to self: your greatest enemy in that fight isn't Vanaduke himself, or the fire, or the minions: it's the godawful camera angle that makes it impossible to see when he's attacking you.) When Sparks were first introduced, I was more than able to keep a net positive flow going, but either I've been mind-bogglingly unlucky recently, or the drops have been nerfed to the point where it's nigh-impossible to keep your head above water. This isn't something I feel like I should be paying for.
Oh, and one more thing: can we PLEASE have it so that people who die right at the end of a boss fight don't get screwed out of tokens if someone picks them up before they revive? I accidentally did that to a party member after beating Vanaduke, and I felt absolutely terrible, because it was no fault of his own.
Found one just yesterday. They don't drop frequently, no.