OP Do not purchase anything the store actually this goes for anyone. I purchased a pack of 3 items/weapons and two were good for a moment until I got a new weapon for my mage from a special challenge and the gold sword from SP. You will get better weapons the more you play trust me. Play co-op as well sometimes you get more. 3 matches and at the end of each match you can get up to 3 items, it all depends. So in the end you can get up to 9 if you are lucky. Sometimes they are good, sometimes they suck, sometimes you get an accessory but sometimes in co-op I've got premium items.
No need to purchase items, they really aren't that good and the ones you get randomly or through these challenges are much better.
^Sig made by Rajeanero