Just added support for Kodak 6800 and 6850 photo printers to Gutenprint. The main difference between them is that the 6850 is faster -- 8s (vs 11s) for a 4x6 print -- and natively supports 5x7 media.
There are many thousands of these printers deployed in self-serve photo kiosks, and they're trivial to find on ebay. Cost per 4x6 print is under $0.17 and media refills are very easy to obtain.
Meanwhile, the 6800/6850 has been superceded by the 605, and the 1400 has been superceded by the 805. If I'm still motivated I may try to add support for those models too..