T/S/S old term of trainer, supporter, stadium, CG is the set acronym for crystal guardian's, and star cards were in incredibily rare pull rate cards where you probably got 1 in 4-5 boxes that go for 50$+ ish.
Yes you could spend 150 on jungle and get the set, but there is already issues going into it, first is the set shadowless, second does it come with with holos, non holos and trainers (funny I should ask because I've seen tons of these "full set" base set, second, legendary, jungle, fossil, rocket, GH, GC, etc sets that only offer non-holo editions or offer just the pokemon without the T/S/S cards, and the ones that offer the full collection go for about 200-300$ and come with at least 1 PSA graded card to ensure that you get a decent collection) though sadly enough your base set and jungle collection have no worth atm because there's a million of em out there making the rarity of the set null and void, due to the fact that the set had been printed for 6 years and has been reprinted for the past 5+ years (since pokemons rise to power). Though yes those sets are cheaper, buying hoenn series to current sets online the box is cheaper, though buying a full set of any neo set online is going to be hard w/o buying the boxes (or they can be fairly cheap but come once in a blue moon). Which cost a miniature fortune apparently, these sets went out of print at such an odd time and they don't try to reprint the sets as much anymore if not haven't as boxes alone cost 1000$+ this being said there is other sets in hoenn and DP that haven't been re-printed making so that those sets intentionally cost a small fortune to buy outright. But for current sets the buyers market makes it so that getting EX's (10-50$) and useful T/S/S cards like virbank, max potion and the like cost anywhere from 6-12$ per card more deck orientated and less collector orientated.
due to rarity of set = cost of singles, Condition of cards = lowered price, and format based cards which makes cards more popular per set = increased intrest in raising the cards value (and it's always usually more then 1 card). And in general, if a box seems cheaper to pull from then buying the singles outright because the full collection would cost 400$. Which I checked CG, 500$ for meh condition 600$ in mint no psa grade, I hit well over 1000 with psa graded cards, ridiculous star cards and ex's, though I bet I could just spend 300 on 4 boxes pull everything I need and spend 100 dollars on star cards and the remaining ex's not including me selling the doubles and double ex's which would let me make some kind of money back (one of the reasons I buy boxes at least I make money back on deck building a collection costs for something that is cheaper then me buying the set outright), DS (delta species made me laugh hard it has 1 more star card but minus 7 exs that CG doesn't have but costs 50$ less on singles due to the ridiculous priced T/S/S cards, transceiver is a minimum of 8-9$, not including the other supporters costing anywhere from 3-6 or 7 dollars a piece.
