There is no way to tell without more info. I moved plumbing in a slab that was $500 and that was 30K. It depends on the location of the drains, ow far you want to move things, and if the slab is post tensioned or not.

To get a better idea, locate your home’s main drain. Then use a floor plan of your house to figure out how the main drain runs to that drain. Then get info on if the slab is post tensioned. Then evaluate the distance that you want to move the drain, in relation to how that main drain traverses the home to the exit. That’s all information that your plumber will need to price, and to apply for the permit to do the work.

One issue that you’re going to have is those copper supply lines buried in concrete. They have a relatively short lifespan compared to those run in a crawl space and are subject to pinhole leaks. It would be prudent to consider a whole home supply repiping with PEX from the attic down, instead of the slab up. Slab leaks are really difficult to deal with, and the cure is repiping. It’s usually at a less convenient time than when you’re already doing messy construction. My 1974 house was repiped in 1990 and the leaky copper supply lines abandoned. 1985 is past due for the issue to arise.

^Excellent advice and I've got a Florida plumbing license. You want the advice of plumbers who have worked in your neighborhood, believe me. Especially if this is a tract home.

Post a dimensioned drawing of your existing kitchen, adjacent rooms, and your proposed island please. You may save the plumber a trip.

We've done it twice, south florida, both homes built in the mid-80's. I'm not a plumber just a homeowner (who likes to renovate kitchens in each house she buys lol) so I'm not sure about all the details that would need to be worked out but for us both times it was very inexpensive, about $500 each time. Both times walls were taken down.

Oh and it's very messy they have to cut deep into the slab... lots of dust and loud drilling.