Depends a bit on what you are looking to do with the holster. IDPA and IPSC have differing requirements, although I think IDPA holsters are legal in IPSC, but not the other way around.
There are kydex (plastic) holsters and leather. I have a BladeTech kydex holster for my 1911 and it works very well. For leather I would suggest looking at Laroche Leathers ( www.larocheleathers.com ) or Penner Custom Leather ( www.pennercustomleather.com ). Neither are particularly cheap, but the quality is excellent.
In addition to the holster itself, buy a good quality holster belt and you will not regret it.
Mark