I kept Garmin Nuvii 360 for couple of years. FYI this was OEM external GPS used by BMW. I used it with free (PKMaps.freeforums.org) which were good but not updated since Oct 2010. Then online I found a cracked copy of Pakistan Navigator, very detailed map, even small towns like Sheikhupura were included. I sold it because I could not use it without reading glasses (eyesight fell).
Garmin is a very nice and state of the art piece of premium hardware and performs like on NOS.
Currently I have this one with Sygic maps. Though the GPS is not as classy as Garmin was, it does the job i.e. well and I like the updated 3D Sygic Maps (same which comes in Altis).
Trakker NAV - Portable Navigation Device
There is another company which deals in Garmin and sells maps for Pakistan (I have no experience with them).
Pakistan Navigator
Though not very detailed, you can download your own GPS maps for Garmin devices from OpenStreeMaps
Free worldwide Garmin maps from OpenStreetMap
If I get good updated Pakistan map for Garmin, I would love to buy one and a new GARMIN device is just a click away