Where can I buy replacement HK speakers for my Range Rover?

Two of the original speakers in my rear doors are blown out and are driving me crazy. We don't have a local dealership (not to mention that I am sure they cost a ton there), so I've been looking online for a good source and have been unsucessful. I have a 1998 which I believe has the 11 speaker 300-watt set up. Thanks in advance for your help.

Did you ever find a place to get replacement HK speakers? I have the same ones blown out in the rear door panels. Thanks.