Who pays for chess engines today?

[Ras]

I have Shredder, but I am not wild about the GUI on Linux (done in Java).

Yeah, I remember that from when I had Linux as desktop OS. The GUI is actually a rip-off from the Mac version. Or at least, it was back then, as a look into the JAR file confirmed. Even with both combined, I guess their market share is too small to be worth investing much time and money.