Insignia Alkaline AA and AAA batteries are 48 for $6.99 .. cheap enough (15 cents per) to replace those in all your mics every time you use them.
AA .. Insignia™ - AA Batteries (48-Pack) - White / Blue
AAA .. Insignia™ - AAA Batteries (48-Pack) - White / Blue
AA .. Insignia™ - AA Batteries (48-Pack) - White / Blue
AAA .. Insignia™ - AAA Batteries (48-Pack) - White / Blue