Jeeze guys...
If the straps broke it could have been where you put them. Sharp edges and temps going up and down in the case, can make like a saw. Over time the metal just cuts through it. If the wires you're securing are pinned up to the metal be thankful you didn't cut through the insulation and short out a power rail.
As for going to Chicken Shack, don't bother. If you want a rugged, meant for a very hostile enviroment type of cable strap, go to something like PEP BOYS or AUTO ZONE. Get the straps that are used in the engine compartment. Same price, better quality. Lasts for years...