By my calculation (base cost of light grav-vehicle chassis + EP cost of upgrades we chose), the chassis will likely be 144 EP, +48 EP for a holofield, conversion shield, and heavy weapon. So 200 EP is roughly right.
By comparison, I estimate a light chassis APC could be around 100-120 EP for 1 heavy weapon, 12 passengers, medium armor instead of light, and a holofield and conversion shield. So there are major potential cost savings available to incentivize designing a new light chassis for APC duties.