For occasional use like that for bows, an Alaskan chainsaw mill is a lot cheaper, if less convenient, and slower. You could quarter the logs pretty easily, or slab them all the way. The saw would also be useful for cutting to length, which a swing mill can't do.
Rather than a bucket loader slabing a log up on site with something you can fit in the trunk of a car has a lot to be said for it, compared to setting up even a portable swing mill, like the Lucas.