In Nairobi we negotiated with a taxi driver about the price he would take us for a half day, and agreed for 4000 ksh (~40 EURO) to pick up from hotel in the morning, do a safari in the park and drop us back in the afternoon. The park fee is about 3200 ksh per person (adult). As it was the rain season (March-May), many roads in the park were blocked by pools of rain water, so the taxi driver and even some bigger vehicles didn't take the risk to cross it. In the end we only spotted antelopes, couple giraffes, monkeys on the road, and an ostrich in the distance. Do bring binoculars with you, as the animals are usually far away, and tend to run away when they hear the car. I recommend to visit this park outside this season.