I bought a kit after sending a colour sample which included: leather cleaner, leather conditioner, 'scuff master' dye, and some stuff for removing the stubbon grease. This cost £48 inc p&p and gave about 6 coats to the front and rear seats. I still have about 1/3 of the cleaner and 1/2 a bottle of the conditioner left too
It's quite easy to do, you've just gotta be patient and take your time.
Firstly you clean the leather thoroughly with the cleaner. I then conditioned it and left it for a day or two. It's good to scrub it with a brush but not too hard. Then when it's totally clean and free from grease you can use the dye. I built up thin layers using a sponge which worked really well. You can use a spray gun with the dye if you like as it needs diluting. Where there are cracks in the leather the dye just fills them and remains natural and retains the softness of leather. Also cos its waterbased and importantly, waterproof, the stitching doesn't get eaten up by any nasty oil based substances.
Then after a couple of weeks I conditioned the leather again and job done.
