I have the canon ip4600, and its very good, here's my story...
I first had rhe 4500, but because I used third party inks, after a few sets the colours went all bad. I.e redc instead of greens etc. I sent them back to a canon repaor centre and they just issued me with brand new 4500 and new set of inks. I did continue to use trd party inks and sent back some 3 printers in total, until the 4500 was upgraded and they gave me the 4600. Right, I decided I was going to stick to canon inks, so had a hunt aroumd and amazon sell the 3 colours inc trial canon paper for 20 quid including p &p. Thats pretty good value. Now for the two black inks, I have found that using THRD party inks is fine. Used 5 sets of black and absolitely fine. Good b&w prints too.Plus the black inks last a long time anyway. So thats what I do and it works fine. Also, using trd party inks DOES NOT invalidate the warranty. Indeed, if you are so inclined you can get a bn canon printer, use the supplied set of ink, then use cheap third party inks for a few sets until the printer does wrong colours(by the way it does wrong colours even if you then put in originals), then call up the cznon repair and they'll come collect the printer and give you a brand new, or current upgrade with a new set of inka free, all in less than a week.
Sorry I went onso long, thought Id let you know my experience!