Where to buy Pokemon cards booster packs and how much does it cost?

You can buy Ookemon cards at retail stores, Target, Walmart.

You will able to find the good options online as well like on ebay, Amazon, blowoutcards. stockx, dacardworld, steelcitycollectibles, tcgplayer, etc.

There is one site waxchecker which provides comparison between these online retailers and provide you the best deal when you are buying trading cards online.

Waxchecker is the home to shop a Huge selection of Trading Cards at Low Prices with an extensive price comparison from Blowoutcards, dacardworld and Stockx.