I got no idea about the cost of anything in your area or situation. You're going to have to do some math, get some estimates. If you can afford it, you really can't go wrong with increasing the size of house. Get a bigger kitchen, which every one wants, bigger bath, even a second bath. Those things not only improve your life, but give the best return on investment at resale time.
If you do get to jack hammering, make sure you know where water and drain lines are. Before starting the hammer, cut along each side of trench with concrete saw as deep as you can to control breakage on rest of slab. Its a messy job, you'll be tracking concrete dust all thru house, or mud if you use wet saw.. Use plastic sheeting to make temporary walls to seal off area, powerefull evacuation fans to get rid of dust.
So you won't have continuous cabinets from new sink back to old location? How long a run of pipes that wouldn't be hidden in cabinets if you did tie in at original? If there is no doorway in between, a 4" highX4" wide "chase" could be built at bottom of wall. It might look kinda odd though.
I dunno if this would meet fire codes but if supply and drain lines have to be in walls, I wonder if they could be wrapped in thermostatically controlled heat tape?
[CENTER][FONT=Comic Sans MS]Measure twice, cut once.[/FONT][/CENTER]
[CENTER][FONT=Comic Sans MS]Look at the nail, not the hammer. Watch the fence, not the blade.[/FONT][/CENTER]
[CENTER][FONT=Comic Sans MS]If you hook your thumb over your belt you won't hit it with the hammer or leave it layin on the saw table.[/FONT][/CENTER]