after i bought a PLB i took a lot of stuff out of my PFD survival kit.a good foil sleeping bag and a big foil blanket and some cord and tape to make a shelter.
my Orange Box stove and a small Gaz cart for heat but no cook gear just MRE "power bars"
having said that if i was going to make a BOB survival kit i would spend my $300 on the best gear i could find and stay away from used or dollar store stuff.
the "break down" bag i carry in my car this winter has my used but still very good down parka and felt lined boots.elbow length mitts and a knit wool cap/face mask will keep me warm until the tow arrives.i got rid of the plastic snow shovel and put a metal one with a sharp square blade in the trunk.
over the years i have come to think that a few really good items rather that a bunch of little gizmos is the way to go.