Wow, yeah, those prices are great. I've wanted a 50A to 2-30A splitter for a while. Just for those rare occasions when I take a transient slip at a marina, and that's all that's available. That hasn't actually happened yet, so I can't justify paying $200+, but for $85, it's a good item to keep on hand to give me more flexibility in plugging in.
I have to admit I also harbor a belief that the name brands are taking advantage of their near-monopoly. If a competitor can charge less than half the price, AND provide decent quality and service, then I want to support them.
It would be nice to actually compare the materials and workmanship with some destructive testing, but that would be expensive. I am concerned to hear that one was so bad it had to be thrown out. It's hard to know from just that one experience if that's indicative of overall quality or just a fluke. Nobody wants to take risks with something as critical as shore power, so we all pay double (or more) what it's worth in hopes of somehow getting "better" quality, not really knowing what that even means.