The Tmo stores have a case by Speck, a belt hoslter case from Body Glove and one other one that I can't remember. Haven't seen anything online, but you should be able to use any one that was for the Optimus 2X.
If you're looking for the Speck case, they have it here for 19.95. That's about 8 bucks cheaper than the Tmobile website shows. If you use code "freeship" you'll get free ground shipping. You can also pick up locally in Glendale,CA for free or just go buy it there. Code
off15" gets you 15% off an item I think. So that may work for you if you wanted faster shipping since the freeship code is only valid for ground.
I purchased the Body Glove case and the belt clip was easily replaced with the provided piece so it fits comfortably in my pocket. I am happy with the case, even though it was $30. Definitely get the screen film protector as well. The sales man gave me %15 off since I bought both.