Your local "pool geniuses" were right. Just the cost of the kit to anchor a dive board properly is about half that cost. Since it is nearly impossible to get liability insurance coverage for any board or slide repair or installation, its surprising they would even consider it.
Take a class on installing a board and you will understand the forces involved on the mounting hardware. What you see as bolts are likely just the threaded portion of a large mounting jig embedded in the pool deck.
My diving board anchor bolts are horribly rusted. I've found that my local fastenal has 1/2" anchor wedge bolts with a pull out strength of 4,400 pounds each. That seems sufficient, so what do you think about it as an option?
www.troublefreepool.com