$32 turned into a small sheet of rubber.  It definitely didn't look big enough to justify the price.

https://www.amazon.com/Vibram-Tania-Protective-Sheet-Style/dp/B00I3LW9K2/

https://www.amazon.com/Bulk-Buy-Foamies-10-Pack-1199-21/dp/B00KDMQB4Y

To save money, work on electronics instead of clothing.  EVA foam &  rubber are what all running shoes are made of.  You too can buy the raw materials, just like China.  Vibram rubber is much harder than ordinary shoe rubber.  The choice of thickness was more due to weight than softness.

The rubber had to be tack glued in places to keep from flopping around.  1mm was thin enough to use scraps to protect the string.

8 miles revealed they were very good for road races.  They were lighter than flip flops.  The foam compressed like flip flops.  They were just as sensitive to rocks as flip flops, but less sensitive than bare rubber.  The most abundant foam is 6mm.  12mm might be serviceable on trails.  The 1mm Vibram  showed no wear.

The foam is a brittle packing foam rather than the tough material a yoga mat is made of.  It's not as tough as the glossy 2mm foam sold locally.  The glossy 2mm might be a good liner for thicker soled sandals.