That's true Brandon, but a complete RB system, including lens, back and waist-level and in good working condition, can go for ~$300 these days. All you have to add is film.
The cost to complete an RB system by adding another lens or so will only add another couple bucks to that price tag. Prisms also don't cost much at all. Backs go for a song, even the motorized 6x8 backs.
When I was touring medium format systems a few years ago, trying to decide which way to go, I tried a lot of different things and ultimately it was the availability of top notch and inexpensive lenses that pushed me to the rb. At the time, I didn't really know much (beyond internet hearsay) about reliability of the various kinds of gear I tried. I just figured that if all else failed, I'd only be out a couple hundred bucks for an rb

Well... the old used one I got is still kicking, and I've come to realize that there is a far greater probability of my brain failing than my rb.
Here's one reason why I think the rb/rz system is so robust: almost all of the mechanical intricacy is in the lenses. The body is not overengineered. The lenses are incredibly robust (yeah, I've dropped a few, and even tried smashing one open with a hammer). The shutters, likewise, are very reliable. I haven't seen any timing drifts or freezups on any of my rb lenses, not even the older pre-C ones.