Homedepot offers RYOBI ONE+ 18V Cordless 4-1/2 in. Angle Grinder (Tool Only) for $49.97 with free shipping. 

Product Description:
Expand your RYOBI 18V ONE+ System with the RYOBI 18V ONE+ 4-1/2 in. Angle Grinder. The 18V ONE+ 4-1/2 in. Angle Grinder offers cordless convenience and the power of 9,000 RPM for rapid material removal.