The Canon MX726 is probably a pretty generic inkjet printer, but it has full duplex printing AND full duplex scanning with a document feeder. I have had this printer for a few years now, and you can put a multi page letter in and scan it in to network or USB.
This printer has helped me move all my files, letters, etc. to digital storage.
You can also get a full set of ink replacements on ebay for about $13.
Does it do duplex scanning automatically or do you have to change the settings everytime you scan?