i have one also. have just finished my first cycle using one and have found it so far really great.
i got mine off ebay and it had 30 sticks included with the monitor. i used 21 sticks this first cycle but apparently i should only need 10 each cycle from now on.
i have just ordered some more sticks tonight, another 30.
i've found that you just have to watch for shipping costs as they range from $6.50 to $26.00 US.