The taxi from Jerez Airport to Jerez bus station around 12-13 Euros. It was a little too much for me so i stood at the taxi stand which is just outside the arrival hall in Jerez airport. In 10 minutes i found another guy who was alone and looking for someone to share the taxi. So, we took the taxi and paid 7 Euros each.
To get from the train station to the fairgrounds of the Feria del Caballo, I took a taxi. On the way back to the station, I walked since I didn't want to spend more money on a cab and the driver of the one I took was rude.