£34!!? mine were £30 for 2!
right, first you need to get the felt lining out slightly where the arch trim meets the bumper. (only enough to get your hand in) there is a little clip there which connects the arch to the bumper (its the same sort of clip tha holds your front grill on).
once youve got this out there is another clip to get off but i dont know how to get it off and cant really see any need for it (obviously there will be but ive driven my R56 cooper round for over 2 years without it with no problems). so i just plled mine off. you will also need about 8 replacement clips for each side. these are about 2p each from a dealer.
to get the old clips from the body work, get a med-sized flat head screwdriver and a hammer, place the screwdriver between the clip and bodywork and give it a bash (thats how i did mine anyways, done it quite alot due to getting my bumper off....quite a lot
hope this helps, someone may come with a better way that just the way i do mine