There's a phenomenon here, and it's actually not unique to us. It shows up to some degree in any "enthusiast" pursuit--I see it a lot in classic bikes, my other passion.
A lot of guys haven't been involved in this stuff long enough to know what's available, or what their options are for doing some particular job, so they just go to a big, obvious place like Moss (or VB or IPD, if you have a Volvo, and so on) and just pay what they ask. It's overpriced (especially from Moss) but it still gets them through.
I'm guilty of this on occasion. A few weeks ago I replaced the timing belt on my kid's 87 Volvo. To do this, you need to lock the crank, and Volvo enthusiasts have figured out all kinds of clever ways to do it. What did I do? Bought the $50 tool from IPD. It did save a lot of time and probably knuckle skin, but all in all, I'm not sure it was worth it. I'll probably sell it on eBay some day, and get back something of the investment. (Of course, if I do, I'll need the sucker next day....!)