Cheapest possible? I know the general range of $30-50 Chinese boards are not ideal, but I also did not know the market on the IBM/Dells had increased as much as it has. It seems as soon as some one mentions alternative keyboards for cheap, the prices skyrocket. The information I based my cheapness older keyboard is apparently dated (less than a year, reported M/Bigfoots for $40-80). As you said, the market has now approached the price arena of a new "entry level" keyboard. I'm not too worried about switch feel, but I don't want the keyboard/switches to fail in a stupid short time either.
The NeXT is close to what I would consider. Probably on the high end, but he's worth it, sometimes

I guess I would need to poke at him a little and figure out which is preferable on key legends. I think he would like either. I have absolutely no qualm with building more converters. His PC also has PS/2 support as well, but he might would like to use it with his notebook as well.
So unless there is some other new platform around that is available in a Hiragana or Katakana layout around the same price or cheaper, I'll keep an eye on the NeXT. Alps are not necessary at all! He likes my blue Alps, but I do realize they are "premium priced" switches. I've never used a brown either, so I'll do a bit of research to see how they compare. He would crap his pants over an Alps board. I don't think he would really notice much difference between Alps or say Cherry, for example, unless the keyboards were sitting next to each other. He would just notice the difference between a dome and mechanical tactile bump, which I also realize can be similar depending on switches..... Oh it makes my head hurt.