well the S2 suspension kit is about £550 I think...and then 30mins per side maybe and then an hour or two set-up ....so £500 + 4-5 hours labour at £50 ...could be well under a grand at a little specialist ...or well over a grand at a dealer, depends on labour rate where you are
Agree that changing the suspension units is very easy...well, so long as you have decent tools in the event of rusted bolts. Just a case of whip off the bolts, slide new ones in, torque them up.