You might not use a power cutter often, but it's very handy to have your own once the need arises. There's no cord to restrict you, just make sure you've charged the battery.
From Amazon
Makita DCE090T2X1 Twin 18V (36V) Li-ion LXT Brushless 230mm Disc Cutter Complete with 2 x 5.0 Ah Batteries and Twin Port Charger
ITS
Makita DCE090T2X1 36V (Twin 18V) LXT Brushless Disc Cutter with 2x 5.0Ah Battery & Charger