Where to get a good RO/DI unit

[BrainVat]

Well I got my tank this far without RO/DI water. But now I'm fighting cyano problems and I'd like to do water changes more frequently.

So where's the best price on these units? I'm looking for:

A 1 micron prefilter
The RO unit
The DI unit
A GAC postfilter
A storage tank of some kind
The necessary pieces to plumb into the kitchen sink line (might rely on home depot for these)

I've looked around on ebay and the prices look good, but they usually want to charge you 40$ for shipping!

-B.V.