There are really two commercial "made for Mobilepro" type cases. An older style and a newer style. Neither is especially cheap, but they are both of premier quality and reinforced and designed to protect your Mobilepro.
The older style case, part number Deluxe Carrying Case S1424-30A-D looks like this:
The newer style case, a much sturdier product, part number OP-MPHH-CASE looks like this:
The case with the older MIPS 780 Mobilepro
Note how the corners are secured to prevent the unit from slipping inside the case. Velcro also is used to secure the device.
The case with a Mobilepro 900 in it. | 
