One of a kind structures are a hit and miss as far as availability. If you only went once you only saw a slice of merchandise. My RR has exactly 61 structures of many varieties all purchased at the Strasburg show. Every one was priced at a "Please take me home" price.
In my opinion, you may want to make Strasburg a habit, each show has it's own "gotta haves". I found coal facilities, icing facilities, many stations, stores, MOW buildings, Many towers, shanties, round houses, water towers, many turntables, small factory, cattle ramps, coal mine, single & multi stall diesel houses, oil racks, crossing gates, etc, etc.