If you don't have any luck,
Wait till sep 22nd, and go to the superactions event at State Fair park, they always have 10-15 dart machines there every time 
Great idea. Do you have any idea of price ranges?? I checked some of the super auctions results posts, but they tend to only focus on arcade games and pins.
Depends on the condition, but if they're working, they will start around the $200 range for the older versions (the ones with the monitor on the front) and head upwards to the $500-600 range for new-ish machines (Valley's, the kind they use(d) in bar leagues). These most likely are from bars around here, since they're switching all the machines for league use to the newer models with 'net access.
Here's a link to Red's Novelty with the new-ish Valley machines that you'll see at the auction:
http://www.redsnovelty.com/Many of the older models won't play cricket, so for a machine that plays cricket (which is what I'm also looking for), expect to pay $300-500 for a
working model, and anywhere from $10-200 for a non-working (or semi-working) model.