This might help. I've don't think the price is determined by age -- at least I don't remember that being the case for any of the families I've booked.
Per person:
Alpine Magic: $179.00
Backstage Magic: $139.00
Bella Italia: $179.00
Cities of Knights and Lights: $179.00
Discovery Down Under: $219.00
Emerald Isle: $179.00
Enchanted China: $219.00
Flavors of France: $159.00
Gateway to the Galapagos: $219.00
Golden Path to Yosemite: $159.00
Golden Path to Yosemite, Signature: $179.00
Once Upon a Fairytale: $179.00
Path to Pura Vida: $159.00
Quest for the West: $139.00
Rocky Trails and Mountie Tales: $159.00
Sacred Valleys and Incan Cities: $159.00
Safari to South Africa: $219.00
Safari to South Africa, Signature: $250.00
Southwest Splendors: $139.00
Spirit of America: $139.00
Storybook Kingdoms: $159.00
Taming the Last Frontier: $159.00
Treasures of Spain: $179.00
Viva Italia: $179.00
These were the prices in August when the tours were first released, so if anyone has different information let me know and I'll update the list!
Dotti