extra? all utilities are in the street, you have to put in traffic control and dig up the street regardless of which side of the centerline the pipe is on. Water and sewer are never on the same side. The cost is highly dependant on the details which you have not given. For instance, is this in downtown Chicago or in Elk Snout? Arterial or local street? Concrete or asphalt? How many traffic lanes and what is the posted speed limit? How deep is the sewer? Is it PVC or VCP? Any other pipelines to cross, like storm drain or gas?
Seriously, if you want a real answer, you need to do some homework and I recommend getting a quote from a local contractor. My answer is about $2k extra