What is maximal different stucture deck can be purchased with gems?

Hi guys, as you knew every structure deck can be purchased 1 limit only with gems. I'm just regular f2p player.

Right now, konami release latest dark paladin structure ex and cyber dragon ex.

I had been make purchasement on 5 different structure deck before. And i wanna to purchase latest deck konomi released. It seem button on latest structured deck with gem purchasement grey out. I checked old structure deck which i havent purchase yet had also occur same problem.

Regarding the question, i think there is some limitation for invidual player isnt it?

Im bit regretful to pick cheap wrong structure deck.