Get hold of a local independent Lockie - Stay away from the big national ones, or any with a big/pretty advert in Yellow Pages.
It usually needs the guy to impression the lock, test-cut, re-impression, re-cut, rinse and repeat many times over until a working profile has been established. He will then finalise the test cut and create a set off that.
Most lockies charge a call-out fee, so if there's ANY way to get either the vehicle or just the lock to him, that'd be cheaper.
If there is an index number on the lock, that could help cut down a LOT of work, as that can often tell the guy what cuts to make. If he has a system like the VAG 66, he may also be able to get the info off the registration/vin/engine/chassis numbers.
Try and locate as much proof of ownership as possible as some Lockies refuse this kind of work without it, to safeguard against theft.
A decent Lockie will be miles cheaper than a main dealer.
With the above info, could be as little as £20 for a set of 3 new keys.
If you need any more help, gimme a shout.