In my opinion, a lot easier than collecting from scratch in the US, mostly due to the difference in packs/boxes and the pull rates of rare cards. A pack is ~$1.50 for 5 cards, and a box is 20 packs for ~$30. There are only three basic rarities (Rare Holo, Uncommon, and Common; as opposed to the West's separate rarities of Rare and Holo), and not every pack has a rare in it. However, on average in my experience, boxes contain about 10 holos and 3-4 EXes. Also, some cards that are Rare in the US are only Uncommon here (like, for example, Bandit Ring's Vileplume). So it's in general a lot easier to get the good cards from a set, and consequently holos and regular art EXes aren't as expensive to buy as singles.
Another factor is the fact that Japanese "theme decks" are totally different and usually contain actually good cards. Generally, Japan's preconstructed decks are released alongside a set and contain cards not included in that set, some of which might be quite good (for example, Dialga EX, Aegislash EX, and Bronzong came in a deck alongside Phantom Gate; the Dragon-type Rayquaza came in one alongside of Emerald Break). They also contain useful staple cards like 4 Professor Sycamore, 4 Ultra Ball, and 2 Double Colorless Energy.
On the flip side, though, pull rates on full arts and secret rares are a LOT lower here, so they tend to be more expensive singles than their English counterparts. So if you care about full sets or blinged-out decks, it can get even pricier here than in the states. But as far as just making a deck goes, I think it's easier here.