I know there are tons of variables with any job, but I'm just looking for a ballpark cost estimate for a licensed plumber to do this, and I know the actual cost can be outside of whatever range of answers are provided.

I'm converting a half bath to a full bath (just a shower).

What is a ball park cost estimate for the rough-in plumbing only for changing the exiting toilet plumbing to shower plumbing, leaving the sink plumbing where it is, but replacing the supply lines and drain lines with new, and adding toilet plumbing in a new location?

Other pertinent facts:
This is not a large bathroom (maybe 10' by 7' overall).
First floor bathroom with crawl space access (approx. 2 to 3 ft clearance in crawl space).
Vent is at sink.
40 yr old house, so 4" and 2" drain lines are cast iron (but will only be replaced where necessary)
Sheetrock and flooring has been stripped, so easy access for drilling / installation.

Thanks for your help. Again, I'm only looking for a BALLPARK cost for the rough-in plumbing so that I can budget the overall cost of the remodel.