The cost depends on the part to the replaced. There are two types of compressor named sandem and valeo are used in skoda cars. I guess octavia uses sanden range of compressor.
The set includes compressor+ clutch+condensor+bearing+pulley should cost around 26,000 + labour. THe labour should set you back by 3000 depending on your negotation skills.
Also another denso compressor avaialble at a lessor cost of 20k.
I recently changed my safari ac compressor. My OEM
compressor and full set costs 17000. I picked up compressor from pudupet for 7k.
If you feel that cost is too high, you can try for used compressor.
contact suresh Car ac T nagar: Phone: 098413 19844. He is a reputed ac mechanic. I did not get my work done from him. I did with the help of my office cabbie.