As of this posting, Homebrew Supply is offering significant discounts on HydroLogic Stealth-RO Systems.  Choose from the RO300 or the R0150.  Prices starts at $209.  No coupon code is necessary.  This stacks with the deal below.

Using RO (Reverse Osmosis) water allows you to build your brewing water profile from the ground up, creating exactly the profile you’re looking for.

Save on HydroLogic RO Systems

Also Consider:

• Hands On: 5 Stage Reverse Osmosis Water Filter by Reverse Osmosis Revolution
• HM Digital TDS-EZ Water Quality TDS Tester, 0-9990 ppm Measurement Range , 1 ppm Resolution, +/- 3% Readout Accuracy
• Water by John Palmer and Colin Kaminski