I picked up a cheapy from a truckload sale at the county fair grounds. Around $35 It's big, heavy and clumsy. As 5twins says on the big stuff like clutch hub nuts, sprocket nuts it is great. Get a set of 6 point sockets to use it with. 12 points can slip.
On clutch spring bolts the hammer powered impact is the thing to use. Works well for the points and advancer housings