If you reuse the sneakernet media then you still can't be sure that no information is getting back. I guess you could burn CDs/DVDs and then shred them every time, but that's slow and has an ongoing cost.

On the other hand, if you use fiber optics, you get better security than sneakernet with reused media, along with greater ease and negligible ongoing costs.

http://ephemer1c.wordpress.com/2013/05/16/data-diode/

The key is three fiber optic converters. Why three and not two? Because the transmitting side needs a carrier signal.

Just set it up and tested it out. udp-receiver --interface eth0 on the receiving end. udp-sender --async --file FILENAME on the sending end. Works like a charm. All off-the-shelf hardware. Hardware setup was a breeze. Anyone with any questions, let me know.