Microcenter has Supermicro Z170 motherboards on clearance:
Supermicro C7Z170-SQ $69.99 (Newegg $212)
http://www.microcenter
Supermicro C7Z170-OCE $99.99 (Newegg $302)
http://www.microcenter
Supermicro C7Z170-M $69.99 (Newegg $79.99)
http://www.microcenter
Supermicro C7H170-M $49.99 (Newegg $64.99)
http://www.microcenter
You can save additional $30 when bundled with an eligible CPU.
Availability may be limited, but lots of stores show multiples in stock.