I use the KJ Works Shadow 2
http://www.kjworks.com.tw for dry fire and it works really well. I have set-up some targets in my basement and I practice the fundamentals (grip, sight picture, trigger pull, transitions, etc.). I use my Shadow 2 holsters but it doesn't sit exactly the same because the trigger guard dimensions are different compared to a real Shadow 2. The weight is comparable with a full CO2 mag. It is a lot of fun.