I asked this question over a month or so ago and someone replied with using distilled water in a spray bottle. Use after all the soap is washed away. I have not tried it yet but think it could be a less expensive route. I love my craftsman blower/vaccume.
Topper
I actually suggested this. After the bike has been rinsed take a quick detailer spray such as Meguiar's and mix with distilled water (50-50 for me). I use this on my suv too and you don't have to spray that much that your hands are going to cramp up. Just spray a light mist on the bike and the quick detailer will help the water run off and prevent spotting. When I was younger I used to detail cars and this was a trick I picked up from a old pro it really helps to prevent water spots.
What I do is:
Spray bike down good with water make sure to rinse off any lose dirt and soak bugs and such well with a little soapy water...kind of a pre soak.
Rinse bike.
Wash bike good top to bottom. Try to save the dirty parts at bottom for last and use a separate wash mitt to prevent scratches.
Rinse bike well.
I like to take my leaf blower to it to get most of the water out of the hiding spots around the engine and tires, rims, and such.
Spray the entire bike with a mist of the Meguiar's quick detailer/distilled water spray. I actually just started using Mother's Quick detailer and I like it the best so far. (This works and it will not take that long you are not trying to re rinse the bike but rather spray a mist to avoid water spots)
Dry with a microfiber towel and use a couple of different towels for paint and separate for rims etc. AND Make sure they are clean!
Go ride and get bugs all over it so it needs to be cleaned again!

IMHO the Mr. Clean system is about worthless. I have a home water treatment system but the only thing running to my outside is a sediment filter which is another inexpensive option. They won't help to much with the water spots.