unipart do them for about £60 i think. Honda will try to sell you a full hub but motorfactor parts are pressed in and then secured with a snap ring. I got j's racing extended balljoints and they fit the same way, been fine for over a year. Another member on here managed to fit a valve or something to keep topping the grease back up in the boot, he had a taxi and was going through LBJ like mad at first.
You'd need a press to get these in, and the old ones out first. Not something you could do by hand, although you could remove the lower arms yourself and just get a garage to fit the LBJ's for you