I used to work in an electronics retail store, you're not looking at the prices wrong at all, it is by far cheaper to purchase a new printer than to replace your ink cartridges, what i used to suggest to customers only printing in black is to purchase a black Laser printer as they last a hell of a lot longer and I am sure they have come down to around $100 if not less, The reason why a new printer is almost the same price and sometimes even cheaper than replacing your ink is due to new printers only coming with "test" cartridges meaning they will not last as long as a new print cartridge and are practically half full, with laser printers they come by default with a full drum and powder unit. if you are just printing off invoices or resume's ect. i would definitely just go for a black & white laser printer.
if you are looking at the colour side of things the ball park changes completely, laser initial cost is by far over the top of the traditional inkjet printers but in the long run are cheaper to run/replace parts.
In saying that you could easily go out and purchase a new inkjet printer and update when it runs out of ink as its cheap, it really comes down to quality, if you are printing photo's the quality is better with an inkjet printer compared with a laser (at equal price range) but printing photo's again comes down to cost vs quality.
I won't go into figures for cost vs quality as its so variable between brands i would be here all day but a rough guide line is the more you pay for a printer in the initial cost the higher the quality and the more expensive the ink cartridges are (usually equalling the initial cost of the printer) and with laser you get slightly less quality, lasts longer and is cheaper in the long run.