Anyone serious about music nowadays wouldn't bother with paper. A full computer monitor is a lot more economical than an ipad & easier to read. There's a 4k monitor for $180.
Just whack a raspberry pi on it. The minimum resolution for a page of music is around 1600 vertical. There are many used monitors in the 1600 pixel range for $50, or the 1920 pixel range for $60. Stand one on its side & the deed is done.
There are 2 surviving 15" laptops from years ago. A 17" one which contained one of the very 1st 64 bit opterons is gone. If the electronics are rearranged, they might become displays.
Reading a single page at a time is not ideal, but the lion kingdom has gotten by with an ipad. There will always be the memory of viewing 4 printed pages at a time.
The trick is a stand for it. Even better would be a music notation program for it & a way to draw annotations.