hey guys-where to get good deal on o2 sensor so i dont pay $220 for a new one

hey can someone give me advice? I got my car checked out, cuz the engine light came on on my dash, and it appears to be that the bottom o2 sensory on the 97 honda civic dx is bad. It is basically not even functioning i am told. However, i can go to autozone and get one for $220 and put it on myself, but i dont wanna pay that much cuz the car is up for sale.....hmmmmm, any ideas?