Most of us love our PT's. Most of us also love saving money.
I don't know about you guys, but saving money had a lot to do with why I bought a PT. (The other part was saving my life with that low center of gravity). I've worked out a compromise that is comfortable for me. I buy filters and spark plugs from my local NAPA. If a hose blows and I need one quickly, I get it from my local hose guy. He isn't any cheaper than PT, but he's right here.
Otherwise, I talk to Keith and Terry. I could probably find a lot of parts cheaper elsewhere with enough research, but my time is worth something to me. Helping keep PT in business is also worth something to me.
PT has a quirky business model that doesn't follow the Fortune 500 mainstream, but I'm quirky too, and I needed a quirky machine. In my perfect fantasy world, PT would provide parts at every Walmart, Lowe's, or Tractor Supply at Low Low Discount prices.
Here in RealityLand, PT does what the boss says. The boss requires retail+ markup on parts. I don't really care to argue with that. The boss is also the guy who decided to risk his money to build these oddball niche machines for those relative few of us who don't fit into the mass-market CUT/SCUT/garden tractor category.
To put it bluntly, I have found absolutely NO evidence of any other machine that will do what I need for a price that remotely approaches what PT offers. Everything else that lifts the loads, doesn't fall over and kill me on slopes, and doesn't rip gouges out of the yard every time I change direction costs something like $20,000 - $40,000 more with attachments.
I'm willing to pay $30 for a throttle cable that might cost $15 or $20 elsewhere. If my tram pump dies, I might spend a couple of hours checking to see if I can get one for a whole bunch cheaper than the couple thousand that PT charges...then again, I might decide that the markup is a fair price to pay for not being tomato paste under a conventional tractor... like my next door neighbor's father.