Converting old-school fireplace

Finally, our search is over and last week we found, financed, and bought our absolute dream house! The offers we received for a new build were so incredibly expensive that we bought a solid house that was already standing for significantly less. The house is in a 99.99999% perfect and renovated condition for us, only the fireplace is a bit "old-school." At this point, we would like a modern fireplace (a freestanding unit with stainless steel and a large glass pane). As you can see in the photo, the floor has just been renewed. Therefore, the idea is to place the modern fireplace on the existing base and cover it with modern tiles. Does anyone have an idea how much something like this would cost? So far, the telephone information from an extremely unfriendly fireplace builder was: "No idea, everything is possible, costs somewhere between 500 and 12,000 euros"...ah yes, clear... At least I already know who won’t get the contract...