I also have a Walther P99 AS 4" and finding a holster is a little more difficult for this gun. You may have enven a little more difficult time trying to find one around the $50 mark. Being IWB you will want something kydex or reinforced so it doesn't collapse after drawing making it difficult to reholster. I have two on order right now, one is a Blade-Tech Ultimate concealment Blade-Tech Ultimate Concealment Holster :: IWB holsters :: Blade-Tech Industries and a TT Gun Leather Reinforced Convertible Pancake OWB/IWB Reinforced Convertible Pancake OWB IWB. I was really drawn to the Comp-Tac Infidel Ultra and Minotaur MTAC Holster but unfortunately they (nor any of Comp-tac's holsters as far as I can tell) are available for the P99. This one was mentioned the other day The Onyx IWB holster for Walther | stealthgearusa. I currently have a Safariland OWB holster with the ALS lock on it and I do like it alot but it is just too bulky and obvious that I'm carrying so I ordered these two IWB holsters. Hoping to get them soon to start testing them out. Let us know what you end up getting and how you like it.