Yes, Garmin offers that option. Before buying the Oregon, make darned sure that:
1) you can load additional maps without wiping out the preloaded maps, and
2) you can plan trips and routes with your computer, using the maps in the GPS. You can create waypoints and routes on the little GPS screen, but it is slow, awkward, and error-prone. No one does it there if a computer is available.
Garmin's older receivers can do neither of these things. Maybe the Oregon can. Find out from Garmin or one of the many authorized dealers that advertise on the web, and please let us know. Most of us buy the maps on DVD, install them on the computer, and load the receiver (or its plug-in memory card) from the computer.