Depends on what you mean by "inexpensive". I've ordered one-off
units from West Crystal and been happy:
Name: West Crystal Company
Address: 10-2550 Acland Rd
Kelowna, BC V1X 7L4 CANADA
Phone: (250) 765-4833
E-mail: wcrystal at shaw.ca
Misc.: www.westcrystal.com