Cool game - we have two 2- lazer blaster sets - 4 blasters in all - for only $40. I bought them a few years back - but never got around to playing with them.
For extra fun, you can insert an iphone or ipod touch in each blaster!
A set of 4 used ones just sold on ...bay for $88
Here is a good youtube review.
https://www.youtube.com/watch?v=9q6326uwnNs