You need to think comprehensively. The cost to do this job in a house where you're doing structural changes and the customers don't expect to use the kitchen is considerably less than otherwise.

How modern is the slab and are there any types of reinforcement in it? That will affect the cost.

Start with a budget with which you are comfortable. Get a good general contractor to see how much he can do for that number.

There is slab, and then there is post tension slab. The latter will be significantly more expensive. It is just a lot of money. I think you should post your current kitchen layout and get input on the layout.

New to kitchens? Read me first.

I don't like the idea of a gas line coming down inside a wall. It seems to me too easy to run a nail through it by accident. If I understand correctly, you are putting the island where the wall was- is there any service to the wall? If electric, why not consider an induction stove? They are as or more responsive than gas and it would be much less costly than slab work.

Instead of an island, you could always have a peninsula and water or gas lines could be hidden in that... possibly a wasteline too (although it would have to drop the requisite amount over the right number of feet to ensure that it drains properly).

1K-20K. Depends on the home's structural elements, and what other associated costs are you counting as part of the project. Like all of the flooring that will need to be replaced. In general, if you are placing an island where a wall was, you don't have the right plan with the proper pathways and clearances. You likely need plenty of help with the design before you go to your bank for the 80K HELOC.

How deep can the island be? Assuming you plan seating at the island, can it be at least 24" deep w/o compromising aisle widths?

What about the width of the island?

.

I think it would be to your benefit to post your layout (in a new thread). I include:

• A measured layout of the space
• A sketch of the rest of the floor the Kitchen is on
• A list of the constraints - and why they're constraints. Include your thoughts about those constraints as you've posted here
• Your planned appliances - and whether you're willing to consider an induction range
• Other info as described in the following FAQ:
  How do I ask for Layout Help and what information should I include?
  http://ths.gardenweb.com/discussions/2767033/how-do-i-ask-for-layout-help-and-what-information

.