Try Auto Factors for the Matrix! Ford were always dearer for them!? Think the 'pattern' ones were exchange, where the Ford ones were outright. Either way, worth a call round the Factors! Got mine from Camberly Auto Factors years ago, they were much cheaper and that was for a Valeo one....
Thinking about it, the 4th bit might of been a metal washer or something? We only used to sell / stock the 2 nylon bushes and the boot...