Buying one-way flight tickets can actually be cheaper because many airlines, especially discount providers, now charge the same price to book multiple one-way fares. And large carriers are facing pressure to be price competitive. The real value in booking multiple one-way flights is you can mix and match them, airlines and airports to get the best price at the best time for you and your kids. Flight aggregator sites such as Kayak.com and Momondo.com can help you hunt for the best bargains. More information is here.