ITA you don't need extremely tall mirrors. MIne are about 5x7" each.
I bought "locker mirrors" at the $ $tore and taped them together with duct tape. Being that they were meant to be portable and moved around, they had a plastic protective edge and backing, which keeps from cutting yourself on the mirror edge. They stay in a bubble envelope in my truck, ready, just in case I see some fabric I want to audition.
So for a couple of bucks and some duct tape, I have what works.
For what I've seen of the "official" mirrors, they are costly and quite fragile. Mine have a lot of protection, and while I doubt they will ever break ... I am not out much if they should. And will go right back to the $ $tore!