The reason Milla is so hard to pull because its a short print, meaning there's only 1 of it in a box. I know, its ridiculous.
I once bought 8 Booster Packs of Photon Shockwave and pulled a Ghost Galaxy-Eyes Photon Dragon. Not the pull I wanted, but I was actually really happy with.
A week later, I entered a local tournament. I didn't do that well, so I only got 1 Booster Pack and a random card. The funny thing? The random card was a Caius and when I opened a pack the pack, I pulled my 2nd Ghost Galaxy-Eyes Photon Dragon. I could barely hold my laughter.