First thing I'd do is make sure where leak is coming from. Often times leak is from a hose or the vane pump. Typically these leaks are on passenger side.
Once sure it's the rack leaking add 1 1/2 oz of AT-205 reseal (don't use a stop leak) to Power Steering reservoir and drive for 5 hours minimum. This will not stop hose leaks, nor have I seem it stop vane pump leak. But works well on rack leak especially on input shaft seal.
If AT-205 doesn't stop leak, look into new or a remanufactured OEM rack. CVJ in Denver is one source. I'd not go with aftermarket.
What install cost will vary by area. Call around to Dealer's and local Toyota specialist. Don't use the corner general auto shop that works on just any vehicle.