What features are you looking for?
The cheapest NEW kit I've come across is the Ion -->
http://www.samedaymusic.com/product--IONIED01
It's not very sturdy and it's not very versatile. I'm not even sure you could use it as a trigger for other devices.
Here's a one-piece:
http://www.samedaymusic.com/product--SINSMI1450
But again, it's not very versatile.