GPS 5 Inch Carrying Case for Garmin Nuvi 5000 1490T 1450 TomTom XXL 530S XXL 540S Magellan Mestro 5310 (DarkBlue) + Wisdom*Courage Wristband
There isn't a big selection of cases available for the devices with a 5-inch screen as of this writing.  Given that, this will do the job.  Not particularly attractive and a little less sturdy than I wanted, although it probably provides sufficient protection.  There is a bit of extra room inside for a cleaning cloth.  On the plus side, it is light weight.  I'd recommend until there's a better choice.