You are absolutely right !... What a guy wants is the standard AD-9 Bendix air dryer. Pretty much every truck shop in north america has one on the shelf. If they don't, they might want to fire the parts managers...
I stock at my work, genuine Bendix (mostly for warranty) and a couple brands of off-shore.
The off shore ones are of course cheaply made, but if a guy isn't really diligent with maintenance, they're the preferred way to go.
Once the compressor starts passing oil, the air dryer is more or less kaput. Engine oil and dessicant don't mix very well.
But a few years back, Bendix introduced the Puragaurd flters, which trap oil, and keep it from getting into the tanks and plumbing.
The off shores we sell for less than 250 bucks. Average life span is about 2 years on the cartridge.
A true Bendix puragaurd cartridge is over 100. But the $$ spent there, saves your butt later on.
Ya got me thinking History...If anyone wants more details...let me know...I'll see what I can come up for a package setup