Are you looking for charter or scheduled? Or do you not mind?
I am guessing you want fly drive rather than flight only if you are staying in a villa?
For scheduled I found that booking with Bon Voyage was cheaper than with the airlines direct. Though if you are a "Frequent Virgin" you get a discount of 10% I think. You can always book a fly drive and then not pick up the car if you don't want it
When are you planning on going? The time of year makes a huge difference to flight prices. Not flying in school holidays will save you a packet
I am flying in August next year and there is no such thing as a cheap flight then, sadly
We are still in the 'seeing if we can afford it' stage but we have no real restrictions on when to travel. Last year we went in May which was lovely weather.
I have always found Trailfinders good for scheduled flights (with ot without car hire but the prices are even better if you included some car hire in it)