Any chance the mini flexible bed corners will be available for sale in the store?
We may eventually but for now you may want to print your own, or have someone print them for you:
http://download.lulzbot.com/Mini/1.0/production_parts/stl_gcode/bed_corners_Mini-flexy/
Why exactly are they printed with NinjaFlex?
Easier to level the bed?
Less conductive?
Heat tolerance?
Just curious 
It seems to work better being printed in Nijaflex and holds the bed snugly in place.