truth is... no one needs 'blind spot' mirrors... you only need to know HOW to adjust your mirrors properly...
Most people look into their outside mirrors and align them so they can 'just barely' see the side of their car/truck. Not correct.
What you should do is place your head on the glass of your driver-side window and then adjust the driver side mirror to 'just barely' see the side of your car truck... then for the passenger side, place your head over the center console (or center) of your truck and then align the passenger mirror to 'just barely' see the side of your truck.
THEN realize that the 'windshield mounted' mirror is your primary 'rear-vew' mirror. As you drive, you will now see that what is shown in the inside rearview mirror is what is directly behind you ... and that when vehicles begin to go 'off the side' of the primary (windshield) mirror, they show up in each of your outside mirrors. As they approach the 'going-out-of-sight' on the sideviews you can see the vehicle(s) directly outside your windows. You never have to 'look behind/over your shoulder' again
It takes a VERY short time to get adjusted to this mindset... and it's the manner taught/used by professional drivers. Try it. You'll like it.
Why look at the same thing in three mirrors? Think about it.