I replaced mine in my 01 z24. I'm a mechanic so I got a deal on parts and the labor was free. However the slave cylinder is located inside the transmission, so to replace it you need to pull the transmission. The book at my shop says 9 hours to remove and install. In my opinion you should get a clutch kit which comes with a clutch disc, pressure plate, and slave cylinder. I know that cost me around 350. Another thing to think about is replacing the master cylinder for your clutch. Nine times out of ten if you replace the slave cylinder the master will start leaking in about a month or two. All said and done your probably looking at 1000-1200 for parts and labor.
The cost of replacing a part is a very general question that unless specified exactly is hard to answer. First, is who is replacing the part? Is the Dealer, an independent repair shop, a junkyard, the guy next door or you doing the replacement. These will all yield different prices. Not to mention that within all of these will be different labor rates and different part price mark ups. Second, what is the quality of the part? Is it a name brand, generic (white box, economy), OEM or used part? All of these will be different. Price will even differ between name brands, sometimes significantly. Thirdly, What is the warranty of the part and who is offering the warranty (the shop the parts house or the manufacturer). Limited Lifetime will have restrictions. Lifetime warranty isn�t always the best part either. Fourthly, Each vehicle can have different options that will affect how long it takes to change a part or make it call for a different part. Such as heavy duty cooling system, air conditioning, 4x4�s may have a steel plate that may need removal, Automatic or manual transmission, the list goes on. Fifthly, What additional parts will be required? Long life coolant or standard coolant, R12 or R134a air conditioning freon if it needs to be discharged or replaced? Additional adapters other fluids that may need to be added or changed? All of this will affect price. Sixthly, is the car a new car or an older car? Labor manuals or guides are set up based on a new car. Additional time may be required due to seized or rusted bolts, additional aftermarket accessories that were installed etc. So you can see where there is a great potential for variances. I offer this insight: If you take it to an independent garage like I always recommend, consider how long they have been in business. What is the quality of there work, are they honest? (see the FAQ how do you choose an auto repair shop for additional insights).