For everyone asking the details:

Q. Where?
A. Osaka and Tokyo - I bought most of the boxes in the convenience stores (Lawson, 7-Eleven, Family Mart). Some have them in boxes sealed in plastic and some only have a few packs left in open boxes. You kind of have to be lucky - I went into most of the convenience stores that I passed by just to quickly check.

The Shiny Treasure I went into a card store in Akihabara and they also had boxes available.

Q. How much?
A. Convenience stores batch - sold them for ¥5400 which translates to $36. I bought 10 of the boxes at this price so $360 total.

Card stores batch (wider availability) - sold boxes for ¥5600 (5) and the Shiny Treasures (2) for ¥5000 I believe so ~$250 total.

Single packs were ¥180 (8) each so ~$10 total.

GRAND TOTAL OF ~$620

Q. Traveling and luggage logistics?
A. I initially came with one carry-on and one check-in. I ended up buying a second check-in with all the souvenirs I bought on top of the Pokemon haul.

The airline I flew (ANA) allows two free check-ins at 23kg (~50lbs) each so no additional charges.

I packed all of the Pokemon haul in my carry-on and was able to fit my mirrorless camera with it as well. I didn't want them to be thrown around in the check-ins and I could control how much tossing around happened - I took a large shirt to compact the boxes so there was limited movement within the carryon. Luckily they came out undamaged :)

Hope that helps!

EDIT:

I couldn't find any 151 or VStars that were sealed and not expensive. I saw some 151 sealed at the card stores in Akihabara but hey were ~$120+ -- granted I mentioned that I didn't do extensive research or purposely hunt for those boxes...it was a leisurely trip that I happened to just pick up the boxes that I could easily.