Honestly I'd just go for the type you get from the hardware - we have cut offs at work and the kids love them. Probably a much cheaper option also. The pipe builders ones would not be much use at the beach as they'd get filled up with sand and that would be it, due to them being so small. I'd get the white pvc pipe in the smallest option - which is about 5cm diameter and get elbows and connectors for it.