eBay. My purchases are no longer listed.  But I did have this one saved in my "watch list" so it must have been the one I used.

Look at this on eBay:

https://www.ebay.com/ulk/itm/321740730451

TOGGLE ROCKER SWITCH ON-OFF ARB CARLING STYLE BACKLIT LED ILLUMINATED DASH CE

They have a rocker switch for Zombie Lights !!!! I'm ordering it ... 

Thought about those myself. Lol
May get that for my golf cart, it has the same light set up as my Z.