If you want quality kydex:
http://www.blade-tech.com/home.php
http://www.comp-tac.com/
If you want quality leather, cowhide or horsehide or whatever:
http://www.kramerleather.com/home.cfm
http://www.mitchrosen.com/
http://www.miltsparks.com/
If you want a quality "tactical" holster:
http://www.blackhawk.com/
http://www.bianchi-intl.com/
http://www.safariland.com/