I always just order them online. I actually was thinking of ordering my next one from this new vendor we have on Canreef, BWI or something .. oh if only I could find one of his posts somewhere.... noticed they also have this cool add-on to make a 100gpd RO/DI a 200gpd unit by filtering the waste water of the first ..more output, less waste .. Check it out:
http://bwiplumbing.com/index.php/rev...ne-add-on.html