This might fit into edge cases. I've used McMaster-Carr as a consumer many times, and though I might get a discount if I bought a minimum quantity, I've been able to purchase what I needed in singles each time. I doubt if there's an e-commerce site out there that will let you purchase and ship 4 screws for less than what you would pay for 200. Even at brick and mortar hardware stores you're ripping yourself off by buying 50 screws instead of 200 (or 1000). I get that you don't need them all but the price per unit is still astronomical.

I bought a bunch of defective keg o-rings that waste CO2 and emptied a keg on to the floor over night (looking at you: More Beer!). For the price of one retail kit, I put together 10 rebuild kits worth of o-rings at McMaster. In that case (5 hours of researching which $0.05 o-ring to buy), the minimum quantity was more a feature than a bug.

I can understand the annoyance for non consumables, like screws.

Meh you can't exactly get one deck screw at home Depot.

It sounds like it worked for you, at least better than all other options that you had.