The drain lines are big, you'll have to either tear the floor off or the ceiling, it needs to be sloped back to the main drain line, so depending on where it is and how the joists run, you may have to box out a section since you can't cut that big of a hole in all of your joists.
If you are lucky, the drain line runs from where you want to put it, so it won't be a big deal other than tearing up things to be able to get to it.
It could be anywhere from a couple of hours to much longer, not counting putting the floor back down, or fixing the ceiling, or building a chase to hide the pipe if it needs to be run below the joists. Then, you've got to move the water supply...could be nearly as much fun.
I had mine moved during a remodel along with moving the tub and sink. SPent about $1200 on just the rough-in, and I had the floor torn up and all of the old stuff removed so they had as clean a slate as possible. This included having most of the drywall off the walls and the subflooring torn up. If I had to pay them to do that, and replace it, it would have been probably tripple that.
Plus, you have to run a vent line from the new toilet location either around the room or up into the ceiling or attic to rejoin the rest of the vent system.