Which Sim card should I buy to activate my unlocked iPhone 6 plus

[iMore Question]

I just bought an unlocked(A1524) iPhone 6 plus but I don't have any sim card for it. I need a sim card to activate the iPhone(make it functional!) but am going to be using it as an iPod touch on wifi. That means no calls, no texts, no internet... . What I really want is a suggestion as to which cheap sim card i should buy to activate my phone. It would be really nice if you could post the amazon link

 

[kch50428]

If not using as a phone, the least expensive one you can find...