You only have two choices in the world of printers: Expensive printer and ink = great quality prints OR cheap printer and ink = poor quality prints. HP is probably the worst anyone could buy. Only their most expensive printers (6+ color inks, large format) do any good for anyone other than home offices. You don't ever want one for graphic design printouts unless you're talking about a large format, like 24"x36" posters. On the plus side, they're generally cheaper, even if you're buying new cartridges instead of refills. But like I said, you're going to get poorer results.
If you want good prints, you're going to want an Epson or Canon printer, but those are going to be more expensive. I don't know what your budget is, but if you want good results, you're going to have to a big investment. I personally have an Epson Stylus Photo 1400 (couple years old). It's a 6-color printer that cost me $200. A full set of Epson brand ink costs me a little over $140 (before discounts), though I only have to refill about once every 3-4 months of frequent use (10-30 prints per week). If I print less than that, they last 6-9 months. If you want longer lasting ink, the Epson R2800 / R2880 is an 8-color printer with high capacity ink cartridges. It can get upwards of 100 more prints than my printer before running out of ink.
I'm not sure about Canon printers because I've never used them, but my former roommate had one similar to mine and he liked it. The only downside was it was hard for him to find ink. But that was several years ago with an older model printer than what's available now.
I print as much as you do, but usually it's not final work so nothing too heavy, but colours should still come out as good as possible. I'm definitely willing to invest in a printer and I was looking at canon ones. I guess I'll pay attention to the availability of ink too now you mention it. Thank you for the detailed reply
The way colors come out depends on the printer head, the quality inks, number of inks, and the type of paper. For example, you're never going to have a crisp, vibrant print on 20# copy paper compared to 100# premium matte presentation paper. HPs are made very cheaply and so are their inks, therefor they have poorer print head technology, poorer quality inks, and their hardware doesn't hold up well. That's why I will never buy one and suggest that unless you're printing out nothing but Word documents or personal photos to put up in your room, nobody should buy them.