A new Rack and Pinion can cost as much as $700.00 to $1,000.00 just for the rack and pinion and then labor costs to replace the rack and pinion are around $300.00 to $500.00
It can vary depending on the make and model of vehicle as well as to the cost of a rack and pinion replacement.
When I had my rack and pinion replaced 4 years ago it costed me $1,200.00 for parts and labor as it's a labor intensive job.
I thought about replacing it myself but it would've been too big of a job for me to do so I let a shop do it.