Having someone or someplace make a custom interior can be expensive in the worst way. True customization, no matter how sweet it is, almost always takes a huge chunk out of your wallet. Having a company make your interior is a good idea and saves you some time (if not money) but if you want it truly done to your specifications, you can always do it yourself.
UPDATE::The foberglass interior idea is taking a little bit longer than expected. I had intentions of finishing it in a week or less but I got caught up in work and haven't even got to start the project yet.