That Lemforder kit posted in the original is much cheaper now than 8 years ago when I did the front and rear suspension on my 1998 528i (E39).
As the cars (E39, E53) are getting older, parts, even Lemforder, are cheaper.
Tips and tricks are below for E39, E53 is almost the same...
DIY: 1998 BMW 528i COMPLETE FRONT SUSPENSION OVERHAUL
DIY: 1998 BMW 528i COMPLETE FRONT SUSPENSION OVERHAUL - Bimmerfest - BMW Forums
DIY: 1998 BMW 528i Complete REAR Suspension Overhaul
DIY: 1998 BMW 528i Complete REAR Suspension Overhaul - Bimmerfest - BMW Forums