your in the wrong forum friend, you should have posted this in Model Railroader forum.
But dont, if you do you’ll have 50 other guys bidding on it. Now beings I came from that inferior gauge called HO before graduating to the big stuff, I can tell you that for a Roundhouse kit, if its complete, $20 is a very good price, but dont be surprised if it goes higher,Roundhouses are still in demand and have very good instructions and any questions that come up during building can be posted on the Model RR forum. Good Luck Vic