I don't think fastenal sells to the public anymore where I live.Brafasco or Fastenal come to mind
Windsor.Where are you located?
BoltsPlus, Spaenaur, Knapp Fasteners (not sure if they do walk-in sales)... Amazon, eBay... McMaster-Carr...
You're probably stuck buying a small box of bolts from most industrial places that do sales to the public.
Another option is a SHCS which is always 12.9 grade. Socket-head cap screw, allen key/hex drive. Maybe try TSC Stores? Or find a friend that can get stuff like this through work for pennies
Sketchy to you but the VW engineers are not idiots and they are stretch bolts for a purpose: during a collision the bolts give and let the engine drop down instead of stay intact and intrude into the passenger compartment (really wanted to put it in a way that really spoke my mind but had to try to hold back)Windsor.
Pretty unreal that the entire weight of the engine and tranny are supported by four stretch bolts. I'm feelin super sketched about the tranny side because I reused em.
reused mine a few times, don't sweat it.