Why is it so hard to find a seat for a 50 panel?
True, I found one on e bay that looked like it was barely in one piece. 200 bucks crazy!
These parts are over sixty years old, for years these were not considered collectable and sat and rotted. Some were hot rodded with seats removed, many were scrapped when scrap metal prices were high. Those that were set aside had to deal with the elements,mice, leaking roofs parts being taken off and lost or seperated and in many cases forgotten and unidentifiable.
Now to the cost of these parts today. Swap meets cost money plus they take a lot of time and effort. The prices are effected by eBay and Craigslist, it's easy to search to see what others are asking for the same parts and they keep going up.
And the fact that these parts are so hard to find and the demand/competition is evident by the amount of requests we see on the stovebolt and the many other forums, $200 for a complete seat may not be that unreasonable
There are a lot more reasons and opinions on this subject and the price that you saw for that item is not fixed, it's just what he was asking for it. Place an ad in the swap meet section and be patient, work on something else until you find the right part at the right price .