Thanks everyone for all your support.  
Another question, though :)

The silvergen site also has a "standard calibration solutions so you can make 
sure your meter is always reading correctly.  A 230 ml bottle sells for 
$11.50"  to go along with the pwt.  Is this useful and/or necessary?  Money 
is not the problem, I just want to stop buying things I don't use/need.

Thanks again.