I don't know if they are a national chain, but "The Rag Shop" has much of the stuff you mentioned, I've gotten some stuff there.

One thing I just did (like just finished three minuted ago) was to re-pack our 72hr + emergency kits using these clear plastic bags that they pack bed linens in. They are super-thick plastic (I'll guess 16 Mils or so) and have a zipper (not Ziploc, an actual zipper) clossure.

I'm posting about the plastic bags to the main forum...

but a linen store was not my first guess at a gearshop!