$600!!! Does it at least use standard size filters or does the manufacturer have some funky proprietary configuration that forces you to buy theirs?
Here's a link to give you an idea, there are many other suppliers, even sponsors on this forum. From the US you of course take a hit on the exchange rate & shipping, so if you can find one in Canada, might save a few $$s.
I like these guys since I've found them to be very informative & helpful with info in tailoring a system to your particular needs without going overboard.
http://www.buckeyehydro.com/premium-rodi-system/
EDIT: Clear housings for the sediment filter(s) are a good idea & also a DI stage that is mounted upright vs horizontal. 75 gpd RO membrane is one of the more efficient at reducing TDS.