Most bang for 600 USD?

[jackflash]

How about a 3D headset with an inbuilt computer, wifi and sensors (gyro, accel, gps and camera) that can superimpose a virtual world on the real world. Add a hand controller that also has gyro and accel. Imagine playing a laser battle or swords and sorcery battle against other players at your local park

[jackflash]

How about a drop in replacement for existing accelerator CPUs using fpga or emulation on Arm or Atom processors, it would be useful to others outside the Amiga community using 68K

[jackflash]

I found an article on replacing old CPUs that uses the 68000 as an example, it even mentions using a modern CPU for emulation
http://www.cast-inc.com/company/blog/post.php?s=2011-06-20-chip-replacement-with-ip-and-fpgas-68000-processor-example

Here is what the article says about emulation
 " introduces new boot code and timing challenges. The effort to resolve these challenges can exceed the appropriate  lifecycle extension budget, consuming any profit to be made in extending  the product’s life.In contrast, simply replacing the obsolete  processor part with a new FPGA device that’s fully hardware and software  compatible is usually significantly easier and less expensive."