Note: I actually recently started working in the printing business & I am simply giving my take on printing.
One of the things that many photographers value is their time. Not only does printing take time, there are other factors that come into play that may make it take up even more of your time (shipping, packaging, etc.). Many of the photographers I deal with (that do online sales) use any one of the following (or all) to tackle this:
Smugmug.com
Imagekind.com
Fotomoto.com (where I work)
While buying a printer for a thousand dollars or so might seem like a great idea, the quality at a service providing professional grade printing is likely to be much better than what you could personally buy (machines are many thousands of dollars) & they also calibrate their machines all the time.
I think it also comes down to how often you have to print (a few times a year, weekly, every few months, etc.).