So, I'm contemplating taking the plunge. Our water system announced that they are starting to alter the water sources for my tap water in April and that I may no longer be guaranteed to get the RO/DI water from the desalination plant. So, by the end of March, I want to get a RO/DI system for my house.
However, I live in a townhouse and I don't want anything permanently installed. I need about 7 gallons of water a week, so I just need a small system and I would prefer something that would install to one of my faucets instead of hard-lining in. So, do I have an option for something that I could hook up for the day before I'm mixing water to a faucet in my spare bathroom? Something small and reasonably priced.

I know I could go to the LFS and buy water but seriously, I never get out of there for less than $100, so that's just NOT a reasonable option. And I don't have anywhere to store water if I bought more than a few gallons at a time.

ask AZDesertRat, i would say that he would recommend the one for $149: http://www.spectrapure.com/email/customer-...eciation.html#1

I have the Typhoon RODI from Air, Water & Ice. I highly recommend it...

http://www.airwaterice.com/c=YkSeU6EzggkBE...Nz0/category/1/

Edit:
I have mine hooked up to a faucet. It's not the most compact unit though.

For a basic reef quality RO/DI the ProPlus is impossible to beat.
http://www.spectrapure.com/email/customer-...eciation.html#1

It comes with a batch tested 90 GPD membrane, 1 micron pre and carbon block filters, full size 20 oz vertical DI with fresh SilicaBuster resin, a dual inline TDS meter, pressure gauge and a hose bib adapter. All you need is a faucet adapter for your particular faucet if it does not have hose threads and you are ready to go.
Your title was asking about the best RO/DI and that of course would be the MaxCap for $100 more, its unique in the marketplace with its individually hand tested and guaranteed RO membrane, absolute rated prefilter and dual DI filters but is a little larger unit, still could be portable though and has superior DI life.

+1 to Spectrapure ProPlus. I also got their faucet adaptor separately and it's a nice chrome one that separates - I keep the top part on the faucet at all times, then snap in the part attached to the RO/DI input line when I want to make ro/di water. Makes it really easy for my husband to use the bathroom sink downstairs when he's working in the office.

I'm not against spending a bit of money. Under $200 preferably. But I'm open to ideas.

The ProPlus is $149 complete, they don't come any better or cheaper for that quality.