Good reply fotofreekwhere are you located? The feedback rating is often dependant on prompt delivery, return policy, and other customer relations issues. Best to stick with known good quality aftermarket inks. That information is in several areas on this forum. My preference is to buy from a vendor that identifies the ink manufacturer. Diyinks identifies their inks as German manufactured but doesn't identify the ink by name. Also, the kit I saw on their site looked very convenient, but it appears that each color comes in several individual containers that seem to be premeasured for refilling a cartridge once. Needless extra containers the cost of which would best be applied to a larger volume of ink for the same price. Obviously, if someone replies to your post with the assurance of the quality you are looking for it would be one choice among the ones that most of us use.
If you've never refilled before, you should do some homework by reading through posts on technique and necessary equipment. Once you assemble your own refill "kit" items you will only need to purchase bulk refill inks.
I just noticed your post and thread about duplexing, http://www.nifty-stuff.com/forum/viewtopic.php?id=6858&p=1 , and see that the sixth post on that thread identified the ink and sources that I've found to be best. Also I see that there was information on some items to make up your own "kit". It was good advice. Why not take it?
As far as the duplexing issue is concerned, my sense is that Canon's reason is more technology based than greed. I would suspect that the mixing of colors to make black uses a similar amount of ink as using black alone. Too much ink would oversaturated the paper and bleed through. Since Inkjet printers area sold on the "razor blade" model, with a low cost printer and high priced consumables, the answer is to refill and eliminate the reason for complaining. That is what this forum is about. Just enjoy beating the manufacturer's system!