Is it just me, or is buying the event Sound Sources not too bad a deal, compared to Outpost Wipeout if you can do the Hard Modes?
For 100 gems, you get 5 runs. If you split it evenly (and over multiple runs), you can get 6 hours each of of dust, credit, and data, on top of whatever you buy from the currencies. For wipeout, 50 gems gets you 2 hours of the above, plus some RE-Energy and gear. I've never paid for additional wipeouts, but I assume the cost goes up the more you do it.
Considering most of us got tons of credit from co-op, we could likely split up the event runs instead for up to 20 hours of dust or 15 hours of battle data.
We'd lose some RE-Energy, and gear fodder, but they seem like a small price to pay for the extra efficiency.