Ventoy is a very good software solution, and not the only one[1], we have also Easy2boot and - for the more technical ones - also "plain" grub4dos/grub4UEFI.
The (very high) price is due - I believe - to the very small amount that they are made, but it doesn't seem (to me) like "rocket science", the basic idea is the same as those floppy disk replacements wherre you can select the floppy image to run/boot.
Some years ago there was a USB stick that had the same capabilities (also expensive as it was almost hand made) called isostick and before that a SD card reader with the same capabilities, simply for some reasons the idea didn't become popular/ubiquitous.
[1] and BTW it has some limits and compatibility issues
The (very high) price is due - I believe - to the very small amount that they are made, but it doesn't seem (to me) like "rocket science", the basic idea is the same as those floppy disk replacements wherre you can select the floppy image to run/boot.
Some years ago there was a USB stick that had the same capabilities (also expensive as it was almost hand made) called isostick and before that a SD card reader with the same capabilities, simply for some reasons the idea didn't become popular/ubiquitous.
[1] and BTW it has some limits and compatibility issues