Well most of the 18650 batt holders out there will only fit unprotected cells, so keep that in mind.
I bought some of this style off eBay.
Even using unprotected cells getting then in and out was a major pain, maybe the double version would be easier.
Plastic Battery Storage Case Box Holder for 2 x 18650 Black with 6" Wire Leads | eBay
The price of the RS/C&K would be fine, but they just don't hold up as well as other switches.