I bought $12 cheap bar end mirrors for my bike. Why? Bar end mirrors take the most abuse. Branches hit them, drop the bike, it hits them, maneuver to close to a wall, you hit them. $50 excellent mirrors seem to break as quickly as the $10 ones in use. I am not cheap, but mirrors are expendable. Even if I break one off, or both off, I can ride homer uneventfully. So I stick to the cheapo's. Oddly, the ones I bought from Amazon are no longer available, so I didn't post a link.
In any case, I highly recommend mirrors, especially if you are on the road. Electric cars can sneak up on you if you are only using sound for car presence.