Searching for an end fed half wave antenna tuner kit on eBay I came across this amazingly over priced product:
Amazing but the reviews are all good (or fake). They've sold 665 of these so that's a pretty good business. What appears to be exactly the same product is advertised for much less if you scroll around.
Peter, VK3YE, has a recent video on the topic of second hand ham radio gear purchasing.
Peter makes some excellent points. You don't always get what you pay for, particularly as technology marches on.