I see..so is it worth to buy lucky box/groove pack? Cause the % to open good item is abit low...
I'd say that if you're gearing yourself up and see something useful or something you definitively feel you need to have, go for it. (I bought December Boxes because I wanted the Vagabonf Wolf costume...bought one at a time and I was lucky I got it in my second box, after that I didn't buy more)
If you have the money to spend you can try buying several boxes and sell the profitable stuff, or save it after the box has gone to increase the price.
I'd say the Groove Pack, while not as spectacular as the Box is good for getting nice consumables, which you can use or sell, plus the 100% sure chance item is great when it's something as useful as certs. (I hate that I missed on the January Groove Packs)
The Box is a good gamble when it contains several popular items, like the December one did.