Picked M&P shield today. I found out that the Galco Summer Comfort and Royal Guard holsters made for Glock 19/23 fits the Shield almost perfectly. Also the DeSantis leather IWB holster for the Kahr PM 9 fits as well, so long as you back out the retention screw just a quarter turn.
So if you have not already shelled out for a new Shield holster, and you have one of the above laying around, try it out, you may be able to save some cash.