RE: Kaos 60 kit by Great Planes
People pay what they want to pay. If it's worth it to you, then the price is OK. For some vintage kits, people will pay quite a bit for them. After all, look what prices people pay for Bakelite jewelry...which was considered "cheap plastic" in the day. Now they're collectors' items. Same for some of the vintage kits. A new-in-box kit from the 60's or 70's (or whenever) that is no longer made can be quite the find.
...and remember, a lot of people would rather build from a good kit than cut out the pieces themselves.