I thought of putting this a part of the Watch Shopping in Malaysia (Kuala Lumpur to be exact) part 2 but then I thought it would be better to do this by itself. I think it would be better to post this by itself as anybody who is going to transit KLIA would be better serve.
We start at the departure lounge (departure terminal). There we find a couple of high fashion boutiques that have watches under their brand. We find Montblanc, Versace, Christian Dior, Hermes and Dunhill. I am not sure if they do carry their watches as I did not visit them. I can confirm that Montblanc does.
There is a stand alone Tag Heuer stall as well. It has all the new releases and some of the older series. The stall is located near the transit train station.
The main shop is Time Watch Shop. They are located near the transit train station. They do carry a good selection of watches that suit every budget. The brands they carry includes (but not limited to) Omega, IWC (includes the vintage series), Tissot, Cartier (good selection), Breitling, Longiness (they have the Legend Diver), Rado, Raymond Weil, Certina, Vostok, Oris, Seiko, Swatch, ck, Guess (and Guess Collection), Mido, Chopard, Citize, Hamilton, Titoni (good to see this brand again) and Fortis (the art series is available).
At the departure hall, there is a watch shop, but I am not sure what it is called. I believe it is operated by the Watchshoppe Group. They carry a good selection of watches. Brands includes Casio, Swatch, Omega, Oris, Tissot, Guess amongst others.
I think those are the watch shops in KLIA. The prices are the same as you would find in the city, that means retail. As for the amount of discount, it depends on the watches and your ability to haggle.