Great game but how much are the extra packs? – Hashi Extreme Puzzles Review

I loved playing all the free packs but when I tapped on the locked extra levels it just said 'enter your Apple ID to purchase' without telling me the price! I wonder how much money that stupid decision has cost them, because this game is super addictive and I want more.
Review by Xbelfast on Hashi Extreme Puzzles.