We were quoted £119 at our local Ford garage to supply & fit the same ISOFIX bracket to our 2010 Focus. The cost was mainly for an hour"s labour (wish I was on that an hour) in turn I purchased the bracket & a Torx T50 bit for just over £22.
Having done some research online & read comments on here, especially those of cs01ttmdm, myserlf & missus armed ourselves with our new car seat, ISOFIX kit & tools, neither of us are mechanically minded.
We also followed instructions: http://www.bavarian-board.co.uk/forum_posts.asp?TID=50238&title=ford-focus-mkii-isofix-installation
The only tricky part for us was: 1) Lifting the rear backrest out of it's fixing (hinge) to get to the mounting holes. How we did it - If you lower the rear backrest so it's lying down (horizontal position), you will see the locking clip it's black with a 'white mark' on it. Using a screwdriver, push backwards (towards the boot), on the clip, don't be afraid to apply pressure as it can be quite stiff. The clip will release & you'll be able to lift the seat about 50mm-120mm.
At this point you may require the assistance of another pair of hands to told the seat while you remove the rubber grommets & offer up the ISOFIX bracket & nuts. Once this is done, drop the seat back into its mounting & push the black locking clip (with white mark) in the opposite direction (towards the driver/front passenger seat), it will flip back, locking the seat. The rest is straight forward.
Tools I used - T50 Torx bit, 3/8” socket ratchet, & thin nose pliers.
I have fitted two of these to my 2009 Ford Focus, they take about 20 minutes to fit and are extremely robust, holding an isofix seat well. The hardest part of fitting is taking out the back seat of the car, I advise having a look on google as once you are looking at the correct part the hinge (a little leaver that can be moved with a flat screwdriver) the seat is easily removed. Once the seat is out, there are two rubber plugs to pull out and then the mount simply screws into the base of the car.
It is really quite simple to do this yourself and save a few quid on going to a main dealer.
You will need to have a screw driver (to flick the hinge leaver), and a star sharped allen key.
Bought for my wife's 2007 Ford Focus, was nice and easy to install, I would recommend checking youtube as there are loads of decent videos to help if you need any, good value for money, only tools you need is a flat screwdriver or long nose pliers and a T50 Torx bit & ratchet.