Will,
Yeah... those servo driven gauges are REALLY nice....... particularly if as you say you are going to do a GA cockpit. But yup..... the cost adds up darn fast. Looks REALLY "real" though.
Although also adding up the cost pretty fast..... I really can recommend the Goflight modules for the main "complex" avionics stuff. The 166 radio unit functions almost exactly like the real thing and it works slick as heck. And if you are going the "autopilot route" the GF MCP is amazing (although it looks visually more like a "heavy metal" unit. Otherwise, simulating those particualr components and functions with "homebuild" is a pretty daunting electrical fabrication project.
How are you going to do the "glass cockpit" part for the GA type cockpit gauge layout? The only GA type gauges that I have seen for "glass" are the ones from Project Magenta. Is that what you plan to use?
I am envious of your idea to go with a "motion" platform. That one is a bit beyond me ;).
best,
.......................john
PS: Ozzy....... the amount and degree of motion Will gets depends on if his lunch is solid or liquid ;).