LEGO Trains is one of the longer running themes that dates back from 1966 and ran up until 2006. During its run there were multiple sets released running on various power platforms from 4.5volt, to 9 and 12 volt sets. Later in 2011 LEGO released additional train sets using RC and Power Functions controllers under different themes like City.
9V consists of 67 sets that ran from 1991 to 2006. As of today,
4558 Metroliner is the most valuable 9V set with an estimated new/factory sealed value of $1,553.
Summary
Trains 9V Crocodile Locomotive set 4551 was released in September 1991, retailing for $50, but has since been retired. New, unopened Crocodile Locomotive sets are valued at $999, while used sets can be found for $247 in good condition.
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