Reaper Miniatures to create a small number of pewter models of the in-game characters. The best bit is that these miniatures were offered free of charge to anyone who bought the game and completed the in-manual proof-of-purchase form that could be pulled out and mailed back. Obviously, whoever originally bought the copy now in my possession had better things to do with their time than tell Midway how often they rented games before buying them, and as such the form is still intact.
special edition boxsets were produced that included a random miniature from the collection. It seems that Dreamcast owners got the better deal here though, as sending the form off bagged you the complete set:
These pewter figurines seem to have been created in pretty small numbers and as such the few that do come up on eBay and other sites fetch high prices. Not sure I'd be willing to smash $300+ on a tiny pewter model these days, but if you sent the form off and claimed your free figures back in 2000, let us know in the comments.