I am considering the same option. I also got an estimate for around $6000.00. I have looked into the drainage system made by Certainteed. You can see it at their website www.certainteed.com. They use it when building new foundations. It looks
similar to the system used by the waterproofing company that gave me my estimate. I need to pour a new concrete floor anyway so I am going to dig some of it out anyway.