Is $18,000 to install full slab quartz countertop and backsplash a fair price?

I received a quote for kitchen countertops and backsplash, comparing a full slab quartz option to a leathered Taj Mahal quartzite countertop with a tile backsplash. The full slab option is significantly more expensive, about $7,900 more than the tile option, bringing the total for the full slab option to around $18,000. I was initially leaning towards the full slab for its smooth, clean look and subtle veining, hoping it would brighten the kitchen and complement the family room, as I'm knocking down a wall between the two spaces. However, the substantial cost difference is making me reconsider. I'm trying to keep things neutral and avoid a look that's too busy or too 'kitchen-y' since the space will be open to the family room. Ultimately, budget constraints led me to choose the leathered Taj Mahal countertop with a tile backsplash.