Hey,
I would choose Taxi, Whirlwind, or Fish Tales over Starship Troopers or South Park. I won't say the price is tremendously out in left field, but they aren't really well-loved games in home collections. For the money, you could pick up a REALLY nice Whirlwind or Earthshaker, and you'd be dealing with give or take the best of the late solid-state games as opposed to some so-so DMD games. To use myself as an example, I have a PinBot, and since I have purchased it, I've bought and sold The Shadow, WhiteWater, Twilight Zone, and two Williams Indiana Jones. The PinBot is still here. Just my two cents.
Luke