0 TDS is not 0 TDS . Read Spectrapures sponsors forum, its very informative.
You will also save more than the difference in initial cost in a very short time due to the extended life of the membrane and DI resin. With my old Typhoon configuration I would be on my 5th DI cartridge now at 150 gallons maximum per cartridge, I'm still on the first one. Add up the cost of all those replacements. I have kept detailed logbooks with every piece of information since day one and I can tell you for a fact, its cheaper to operate and gives you much better quality water. I have proven this with a lab quality benchtop Thornton conductivity/resistivity meter and flow meters. They jsut don't compare.
The best way to buy it is get in on a group buy so you save moneyon the initial purchase like I did. Talk to Randy Holmes Farley on the quality and longevity, his Spectrapure membrane lasted almost 10 years before replacement! Thats a testimonial to the quality of absolute prefilters, good carbons and hand tested RO membranes.