They are held in place by one Allen bolt, all you have to do is remove the wheel, unplug the wiring connector behind the bulkhead and thread the wiring through from the wheel arch. Should take you no more than 30 mins each at home, I would expect a tech with proper workshop facilities to do it in less. $300 for labour? He's having a laugh. Bring the car round to my place, I'll swap them for 250!
'08 Chrysler 300CRD (MB OM 642 engine)
'95 E220 estate
'89 230TE (R.I.P.)