There is a special tool for doing them, so purchasing this is usually only a bit cheaper than getting a garage to do them, dropping the axle from its mounts is easy, as it can hang from the rear shockers. Some press out easily and others can be so tight they need burning out. I would expect to pay 2 hours labour to have them changed by a garage.
Generally i think the non OE stuff is ok, but with these bushes i would buy OE as they tend to last fairly well.