I can get a new DVD for my '03 LC, $200-ish. It goes in a box under the driver's seat. I've not heard of separate DVDs for different regions.
Most enthusiasts seem to prefer non-nav. When the nav system gets obsolete or malfunctions you can't replace it if it also controls your A/C and radio etc. Right now I'm wishing my LC had USB ports for charging and playing music/videos, wishing my nav database included new highways and neighborhoods in my area, and various other modern functions. If I didn't have nav I could put a nice entertainment system and GPS in my dash for not a ton of money.