Pitons

For a newbie big waller if I was to invest in a bunch of pitons just to play with and maybe do some of the easier big walls on el cap what should I purchase?

https://www.petzl.com/CA/en/Sport/Anchors

I've provided the petzl link only because i was on it.  Would of course purchase from other manufacturers 

I think most routes there have been climbed with pitons, so I'm sure you will have a blast!

Go with someone experienced who already has pitons