What do you need to get minecraft on pc?

You can buy it online at Minecraft.net

I have seen giftcards at some shops like walmart of gamestop that will let you buy the card for cash or whatever currency you can spend, then apply the code at the same website that "Sam" gave you to buy the game without having to give credit card information over the Internet.

All you need is a credit/debit card and head over to minecraft.net. Make a free account there, pay for it once, download and install from the site. Once you get it up and running you can choose to play online or offline. Only difference is playing it offline disables access to whatever servers you wanted to play on. Awesome thing about minecraft is if you change computers you can just download it again. No need to buy it all over.