I bought a pack of cards when I got the 40 free tickets, and got a premium shield that I've been using ever since (Champion's Kick Mitt, currently around 700 guard and antimagic at lvl 5). I didn't find any premium items, except for a boring helmet, for a long time.
Eventually I played through most of the story and got a few good items from there, and on an occasion or two I've gotten a good item at the end of a match.
Anyways, if you're really desperate for more/better items, save up some stars and play the Happy Spinner. Sometimes you get premium items (I have no idea what the odds are), and you at least get more crap items for upgrade material.
"Although wealth may not bring happiness, the immediate prospect of it provides a wonderfully close imitation."