What would be even cooler is if, instead of only selling the things, they also offered either a 1-month lease, or a buyback and refurb business. How many times would the average person actually use this, anyway? I'd look at it sort of like chamber reamers; well worth putting down the full cost as a deposit, but even better to get 75-90% of the money back after the one or two uses I'll ever need it for.
Failing that, a pass-around chain could easily be started, but lacks the protection inherent in having it return to the maker to be rechecked and serviced if necessary between users.
Once you build/assemble ONE, it's a sickness.
You suddenly realize you could use, or would like to have, a full length 20" dedicated scope/optics/precision/varmint type rig, a harder hitting 6.8SPC, maybe a 10" Sig Brace "pistol" build for fun or SHTF/car carry, then maybe a .300blk is suddenly interesting to you if you're thinking about a suppressor, because you realize you've got a bunch of leftover .308 projectiles left over... Then there's the .22LR builds...
Besides from the nearly infinite number of variations and customizability, probably the biggest factor in the popularity of building AR's is that you can spread the costs out over time as your paycheck or the wife allows it, pounce on deals when you see them, and if you spread it out over time, you learn of new parts or accessories you hadn't thought of before, so the build winds up being something you hadn't even considered by the time it's done.
Then maybe after a few builds, or you change or upgrade a few parts, you suddenly have enough leftovers
for one more whole other rifle as a beater, spare, or backup, and all you have to do is buy a $39 blowout fire-sale lower, or build a new 80% lower to put it together on.
They start multiplying on you.