Sure, 100k for 1 language sounds odd, given that 200k was enough not only for 2 languages, but also the entire framework. Still, the overall price point is more than fair.
You have to take into consideration that Light Table aims to be specific; adding further languages will likely result in more efforts than merely adjusting an IDE a little bit.
Do a search for "Pluggable Backend Infrastructure for ClojureScript, and Development of a Lua backend" and you should turn up a Google Summer of Code 2012 project which seeks to broaden the scope of the ClojureScript compiler. If that project is successful, and if LightTable supports ClojureScript, the IDE's reach may be greatly expanded in the relatively near term.
I'm just saying they claim to be "highly extensible" and yet, support for a new language requires a development effort of 100k.
It's sad since I mostly code in ruby or scala, these languages won't be supported and I don't think anyone is going to make a 100k development effort to support them.
Just because it's highly extensible doesn't mean that beating the other language's VM into doing what's needed isn't going to require a bunch of effort.