You can usually put an internal hub on any bike with horizontal dropouts. Vertical dropouts take a bit of skill. I have seen internal hubs on a Swift. Owners had no complaints.
If you are going to pack a bike up alot, an internal gear hub would be a plus. You will need a wrench to remove the rear wheel, I do not think there are QR work on internal hub wheels. Try Dahon, 7 speed $150:
http://www.campingworld.com/.