From the reviews I have read the G6 is a good camera. Everyone I spoke with and what I read said it put out great quality photos & had good macro capabilities. It is also supposed to have decent performance - especially when taking RAW pictures - compared to other cameras. I had originally thought about getting the Oly 8080, but when I read that the 8080's RAW performance was really slow, I changed my mind & put the G6 at the top of my list.
What I didn't like about the G6 was that it isn't using Canon's new DIGIC II processor, which would make it perform even better & it's video recording features are limited in frame rate and the amount of time you record, instead of being limited by the size of the memory. I did want to have a camera that did both good video, took good pictures, had good macro & had good performance.
I ended up deciding to go with the Canon A620. I know it doesn't have RAW, but I decided that until I get good with taking pictures & I decide how much I am really going to get into this, I wanted to keep to keep my costs down for now. So, since the A620 got good reviews on picture quality, has good macro ability, shoots good video, & seems to perform well I decided to go with it. I was able to get the A620 camera, longer life batteries (with an extra set), charger & Canon's underwater housing for $500.
The G6 was about $500 on it's own. There is no Canon housing for it. The only housing I found was from Ikelite and it ran about $600 putting the total just to get started around $1100. Which was more than I wanted to spend, until I know how much I am really going to get into this.
As for where you can buy the G6 - I have seen several online camera stores that have it. At least they did a couple of months ago. If you can't find them now, StevenB is right - e-bay will have them. I have looked there many times and there are always some available. Many of them on e-bay are brand new. It seems some camera stores sell new items on e-bay as another avenue to get sales. Theses stores advertise them on e-bay as new in an opened box from the factory and they come with full warranty. I have never bought from them though, but many have high e-bay ratings as sellers. I usually see the winning bid around $430-$530 for the G6.
Anyway, good luck in finding the right camera for your needs,
--Mike