3 keys isn't a wide range, lol. The minimum range that is possible/likely to be accepted is two keys usually. And not all unusuals are rare. The older effects are all very rare, as there is a 9:1 chance of opening a new effect when unboxing from crate 26 or newer. If you look at a hat like...a steaming hetman's, there are a lot more that exist and are on the market. With old effects, most are either in collector hands or are in inactive BP's. And also, that one link has TWO MONTHS of offers, and is bumped regularly.