As Gail says I recommend Epsons. If you want to print your digital images you want a printer that the ink has archival qualities. You don't want to print your pics and have them fade in several years. Not all printer ink has archival qualities. You may buy a printer with cheap ink and save money today but your photos may not be around in several years.
A great place to learn about archival issues and printing is
http://www.wilhelm-research.com If you use the Epson photo printers that have the archival inks you can expect your pictures to last longer in many cases that traditionally developed films. Costs to print your own photos compare to taking them to the store. By printing your own you only print the ones you want, you can crop, enhance the image, etc. You also can print any time you want. If you decide at 2 AM that you need to print Grandma's photo you don't have to jump in your car and run to the store to get them printed. If you are into scrapbooking Epson inks are acid free and they have many acid free papers. Traditional prints are not acid free.
Some things to keep in mind when buying a printer, you should always use the paper made by the manu. of your printer. Paper and ink are designed to work together. Ink needs to be sprayed on the paper, soak in and dry at a precise rate. By using another paper they may not happen. You may get prints that don't look right or they may take a long time to dry, etc.
As far as the one ink tank vs. separate, with photo printing you aren't going to see a lot of cost saving by going with the ind. carts. In photo printing you tend to use your colors fairly evenly. Unless you are printing a lot of things that use one color the sep. black and a sep color tank system will be OK. In my experience if one color runs out another one shortly follows. When you have separate inks you aren't saving lots of money because you still have to buy the plastic tank that houses the ink.
The Epson's are reasonable in price for the ink because the print head is built into the printer. Many of the companies put the print head on the cartridges so that makes the price higher because you are paying for technology every time you buy a cartridge. People will argue that this way you get a new print head every time. Epson builds their print heads to last where the others build them to be used once and thrown away.
As far as the dpi you will see quoted that is a nice number to know but most of the professionals never print at the highest number. The Epsons are capable at printing at 5760 dpi but usually the highest I print at is 2880. You would have to look long and hard to see a lot of difference between 2880 and 5760 but the time to print increases and it uses more ink.
Epson makes printers with 2 different types of inks. Dye based or pigment. Dye based will give you a brighter more realistic look but pigment will give you even longer archival life. Pigment is the way of the future but the inks are still being worked on. Dye based inks have been around forever but an all pigment ink printer has only been around for 2 generations.
To me speed is the last thing that I look at. People will ask me how long it took to print the photo. Truthfully I have never timed it. I just know when the photo comes out and it looks beautiful I am thrilled. It may have taken a few minutes but it was worth waiting for.
So now you have to choose between an all around printer or a photo printer. Epson makes a 4 ink or a 6 ink printer. The advantage of the 6 inks is better photos. The C64 and C84 uses dura brite pigmented inks so your printouts on plain paper are waterproof. In the Photo line they make several models. The Photo 820, 825, 925, R300. If you want a wide format printer I suggest you look at the Photo 1280 or 2200. They will print 13x19.
A great place to buy printers and inks is
www.atlex.com They sell ink for all the printers and their prices are better than the stores even with shipping. That is where I buy my supplies.
If you have any questions I will be glad to answer them for you.