According to Michelin, there are three tolls along the way costing 6.90 euros in total.
http://www.viamichelin.com/viamichelin/gbr/dyn/controller/Driving_directions#startLocid=3bMDlSRVAxNjk5Njg2U0VSUkVQMTExMGNNell1TmpjME5EQTJjTFRRdU5Ea3dNemcz&destLocid=3bMDhSRVA0MjAwOTZTRVJSRVAxMTEwZ016WXVNREF5TVRjMU9ETT1jTFRVdU5UUXlNamM9&step1Locid=&step2Locid=&vh=CAR&distance=km&strVehicle=0&intItineraryType=1&devise=1.0|EUR&isAvoidFrontiers=false&isFavoriseAutoroute=false&isAvoidPeage=false&isAvoidVignette=false&isAvoidLNR=false&carTypeHidden=Citadine&caravaneHidden=false&typeCarbHidden=essence&autoConso=6.8&villeConso=6&routeConso=5.6&carbCost=1.3&dtmDeparture=05/03/2008

Nice one, thanks.
Very useful site.

We travelled to Gibraltar last week from Benalmadena. We drove down the coast road (very scenic) but travelled back along the toll-road. I'm quite sure we paid three tolls at around 8 euros in total. Some parts of the road are toll-free.

Depending on the time of year toll charges on the autostrada change. 3 tolls are correct - but the prices are around 11.50 euros fifty these days one way down to Gibraltar (and back) from Malaga Airport. Its the middle toll around Marbella that is the expensive one. You can take toll road and coastal road or a bit of both. Always good to see the scenary on the coastal road but the area around Marbella can get quite congested. The road signs are reasonable on the autostarda that tell you slip offs for coastal road. Q's at the border have diminished a lot now due to better controls - but sometimes it is worth just leaving the car parked along the front in la linea and walking across border with passports. Buses run regularly opposite the airport up town...and the airport is less than one minutes walk to the border.

Nivsy