M5 MacBook Air upgrade pricing

Can someone please explain this pricing for the new M5 MacBook Air 13”. (This is US pricing, but I’m seeing a similar pattern in the Canadian store)

10 Core GPU Chip, 16GB Memory, 512GB Storage = $1199 (Note that this is the higher chip that allows for memory and storage upgrades)

Upgrade above to 24GB Memory = $1299 ($100 increase)

Upgrade above to 1TB Storage = $1299 ($100 increase)

Upgrade above to 24GB Memory AND 1TB Storage = $1499 ($300 increase)

Is this a glitch or am I missing something?