Depends on where you plan on wearing it. For the typical strong-side "FBI carry" in the 3-4 o'clock position, you probably want something sturdy. I find that for "appendix carry" in the 1-2 o'clock position, a flimsy holster works best for me. I use an Ace Case non-tuckable, $17 or 2 for $20 delivered. Another slightly less flimsy alternative would be one of the old Bianchi suede IWB models, I'm getting ready to give one of them a try.
The nice thing about these is that if the holster itself or IWB carry in general doesn't work out for you, you're not out a lot of money.