I checked with my distributor. (Prices are given in a range to avoid narrowing down which distributor exactly it is)

Jagwire basics shift housing (Bottom tier, unlubed housing): $.25-.29/ft

Jagwire Sport shift housing (mid-tier, lubed housing): $.30-.36/ft. Also the nicest traditional shift housing Jagwire offers.

Jagwire Basics brake housing (ditto): $0.17-0.23/ft

Jagwire Sport brake housing (ditto): $0.24-0.30/ft

Jagwire Pro brake housing (Nicest traditional housing Jagwire offers, compressionless): $0.80-1.20/ft

Shimano OT-SP41 shift housing (Good stuff, specced on everything up to Dura-Ace): $.33-.39/ft

Shimano SP51 shift housing (Basically SP41 but 5mm): $0.60-0.90/ft

Shimano Dura-ace brake housing (Dura ace): $0.40-0.49/ft

Shimano SLR brake housing (Normal stuff, good quality): $0.36-0.45/ft

SRAM brake housing (idk, never used it. Seems to be on par with Jagwire Sport): $.23-.27/ft

There are only 2 housings that cost more than $0.50/ft in bulk, which are Jagwire Pro compressionless and Shimano SP51.

OP mentioned that the shop claims they use the "best housing and cables", but even so there are a few important reasons why they're almost certainly not using Jagwire Pro and Shimano SP51.

Jagwire Pro is a slightly larger diameter than standard for brakes, and won't fit in many standard brake systems. In fact, they need a special cable extension for road brake levers and a special "Point-of-Power" ferrule to actually interface with the brake calipers.

Shimano SP51 is no better than SP41, but it is larger. It's designed for legacy systems that used 5mm coiled housing for shift cable. Most modern systems, again, won't fit the larger diameter of the housing in their shift levers and derailleurs.

So yes, distributors don't charge $.50/ft. In most case, they charge quite a bit less.