If you need to buy brand new keys then I doubt there is any other option other than to go back to the dealer and it wont be cheap. Will probably best part of £200 including buying the blank key and then approx 30 mins of main dealer labour to program it to the ECU..

If you had the original button keys there are procedures you can follow yourself to re-programme them to the car, after you've replaced a flat battery for example but those keys are already coded to the ECU, brand new keys will not be and that's the bit the dealer will have to do.

'blank' three button keys are available pretty cheaply on the internet (Ebay) but not sure how they would work with the car if they are not genuine ford keys.. but that's probably the cheapest option, buy the blank keys yourself if they will work ok and then you'd probably have to swallow the main dealer labour to program them to the ECU..

http://www.ebay.co.uk/itm/3-BUTTON-R...UAAOSwrklVbf4I


That's probably why there are no keys.... lol....

Happy to be corrected but that has been my experience of doing this on my Focus a few years ago..

HTH