Between 5 and 30,000 dollars, it all depends on the quality of the product you want. As well as what you want. (Eg. Gas fire pit, low voltage landscape lighting, etc.)
What Achilles said. I did one similar when I was working construction in my sophomore year. No electrical ran through it. Ours was nowhere as intricate with the various sizing of the bricks, either. All together, I think we charged it at$8,700. Was 2-3 years ago, though, so my memory could be a bit faulty