So here's the problem, you could buy 50 dollars in energy, and craft a few hundred things and just be out.I understand a few hundred sounds like a lot, but look at any other MMO and this is not the case. I'm not saying Spiral Knights shouldn't be unique in it's crafting system, it's levels with tiers and all is different from many mmo games I've played but the fact is no amount of money could actually cover everything, which is very bad for business on three rings part. Any other game I've ever seen can be covered with money ( and not much ), and it's because some people just don't want the hassle of the free feature.
I think a $5 a month optional fee should cover all personal energy costs. If a game as big and versatile as say runescape can be 5 bucks, this fairly simple game should be able to as well. It's not a QQ factor, it's a - people aren't going to play this game if they either have to dish out 50 bucks a month to be a serious t1-t5 crafter, or get extremely lucky on Unique Variants to be able to sell for their energy. Many people, myself included want to just dive into a game, and do everything they can constantly. This game doesn't allow that without a whole lot of money, or if you get good mats down in the clockworks, a LOT of trading time.
Also, I think energy should also still be tradeable and buyable by people who subscribe, but only for trading purposes.
Edit- I've also had a few friends already say 5-10 bucks a month would be no issue to them, and I'm sure three rings knows this game is fairly simple and could charge lower costs than huge mmos ( WoW, Everquest, warhammer )
Uhh, if you are crafting a few hundred items, you should be selling those items and buying CE back, if not selling directly for CE. There are plenty of people in the game who have managed to become completely independent with a starting bank of only $5 in energy.