For several years I have been purchasing my limit of Treasury I Savings Bonds. I intend to go on buying the limit each January, as long as I can. TIPs can and do sometimes decline in price. (I think a short duration TIPs fund, such as VTIPX, may be a sensible alternative to a short term CD) I Bonds increase in value every month according to changes in the CPI, the variable rate of interest being updated by the Treasury every 6 months.
A credible source of information and analysis on inflation-protected Treasury securities is David Enna
http://tipswatch.com