There are two types of armrests available to you.
A cloth version which i know you dont want and a leather one.
I am unsure on the exact part number for the leather but price wise (undiscounted) the cloth is 115 inc vat (1m0061100g) and the leather version is 145inc vat.
Now there are a few naughty people on here that will lead you to believe that you cant buy it as a single unit (TT
shop wanted £355 for a cloth one ~ utter joke), but you can ~ kit includes main centre unit (pad and base) and brackets / screws everything you need for fitment. I fitted mine about 2 weeks ago ~ best thing i ever did. Ring a Seat main dealer, i have fone numbers if you need a good one.
You will have to cut out your rear coin tray with a standing knife to fit the armrest, which is easy to do providing its sharp and your patient. The bracket fits under neath the plastic centre console with three bolts and pokes out the top of the coin tray. You will then need to attach the top piece which is a d lock and screw (in the kit obiously) just make sure that it engages properly into the bracket or the screw will not properly go all the way in and obstrude the ash tray.
PM for advice.