we do it ourselves and use flightchecker type sites to work out who flies there the cheapest. however august? firstly you might struggle to find a flight as every where this year is booking way earlier and secondly it is the peak of peak season. if you don't care then get a bucket flight to somewhere in spain and look at getting a bus the other end. or book a coach trip but it is long and dull but cheap.
We are tied to school hols too. I now generally book low cost flights first (I've now learnt that they are cheapest as soon as they are released) and then book accommodation and transfers either directly or through Travel Republic. I don't know what your budget is, but we generally spend around £2000 for 4 of us (kids over 12) for flights, transfer and accommodation.
If you don't mind mid-sized-busy resorts, Mytravel usually do some cheap packages. We prefer smaller resorts though.