Yeah, this is one of the few sets to have a sub-set (Radiant Collection) within it. Don't quote me on this, but I think you always pull two Radiant Collection Cards in a booster, and with this being a 32-card mini-set, the odds are you'll get one of the better cards quite often. Even some of the Uncommon RC Cards are holographic and look like Rares, such as the Charizard, Yveltal, and Diancie.
I'm friends with the Organised Play Manager at The Pokémon Company International and she informed me there's definitely no plan to release a booster box for the set, so I think getting one of each of the collections released this year is the best starting point. You'll get all 18 Promo Card versions, 11 Pin Badges, four Jumbo Cards, 65~ Generations / 20th Anniversary Card Sleeves, an Elite Trainer Storage Box, 45 Generations Design Energy Cards, some other tidbits, and of course, 48 Booster Packs for an investment over the year of about £260~. Though, I'd probably go for a second Elite Trainer Box if I were trying to fill the set, so you'd have enough of the Generations specific sleeves to store the cards in and top loader them.
Due to the set being 115~ total cards, you'd probably only have a handful of gaps to fill! Also, opening the packs will feel less disappointing than a lot of other sets, since you know you'll get a lot of pretty cards
That Jolteon EX is probably worth keeping an eye on though!