Your comparable options are to hire from one of the on-airport companies. Those are (basically) Avis/Budget, Europcar/National, Hertz and Atesa/Enterprise. These are all unlikely to be less than Motoluis this month (probably more), but the cars are there in the car park opposite and you can return them at any hour of the day/night by leaving the key in the drop-box.
You can sometimes get discounted quotes for the big companies by looking very carefully at intermediary websites which specify whether there's a shuttle bus as against on-airport, plus they are all full-to-full fuel policy so that helps you spot deals on them. But watch the excess liabilities (Budget/Avis is very high - about 1,400Euros on a Seat Leon) and definitely insure them separately if you can because the extra premiums some of these companies offer still exclude tyres/glass/misfueling etc. etc.
Also their pick-up offices all close at midnight so you can't rent between then and 7am. Depending on where you're staying you can also get a cab to the hotel and then go back to the shuttle bus office for the car next day when the kids are happily stowed with an ice cream by the pool. Bit of a dent in the holiday for the driver but if you're there 10 days it probably isn't critical. Means you can drop it back to a shuttle bus office when everyone's calm and relaxed on the way home.
