i've got the yankee tool pex crimper and it rocks. does 3/8, 1/2, and 3/4 and only costs about $40.
i wouldn't use anything but pex crimp rings for pex tubing, but maybe that's just me. those push fittings make me nervous. in my county no type of push connector is approved for in wall applications.
also, check your local plumbing supply store rather than lowes...you'll find the price of rings and fittings to be about 1/3 the cost of lowes.