[iancmceachern]

Yes, it's unusual for professionals, just fine for hobbiests.

Because of reliability, etc.

For the same reason you wouldn't order your ingredients for a professional Michelin starred restaurant from Amazon.

I've almost never found Amazon cheaper either. The sellers on Amazon are almost always not the original manufacturer, they're usually FOB folks who are just buying big boxes of things and then selling them individually.

You're almost always better served to swim upstream and get things from the manufacturer, or from reputable electronics distributors like digikey, Farnell, mouser, jameco,etc. A quick search at some of those and I'm finding suitable solenoids at $2-5