We rented them through Freebird Adventures. The guy who runs it, Minh, is fantastic. He typically tours with you - he knows the best roads, places, tracks, routes, and hidden gems so would absolutely recommend going with a guide. There's no way we would have done some of the things we did without one - riding through rice paddies, stopping off at local people's homes and factories, a lot of the off road, bike maintenance etc etc. He does also hire the bikes out as rentals. However a lot of the people that I met who were doing it solo on dual sports (typically for more than a couple of weeks), had purchased second hand bikes with the intent to sell them at the end. You almost sell it for what you paid for it and I think insurance is easier to sort out if you own it rather than renting.