Unless you are buying new, it's tough to justify the cost and complications or retrofitting a built in generator. Even new, they ain't cheap.
Realistically, you are looking at 4-10 times the cost and if you need work done on it, you either have to as the saying goes, take mohamed to the mountain or the mountain to mohamed.
If the weight of moving it around is an issue, consider having a mount made to attach it above the pin box and get an electric start model with cover. That will give you 95% of the convenience at 20% of the cost.