If you get the achievement for the class with all the items you need from it, you can re-buy the items again with gil if you ever need to toss them out. And I'd bet all my gil in game they won't change the pricing of the items. They've been out for years basically, so they won't cater to the latecomers. Only difference is the Saucer ones are lv1 and non dyeable
Gear Slot Wolf marks
Weapon- 4,000
Head -2,000
Chest -4,000
Hands - 2,000
Legs - 4,000
Feet - 2,000
It's 18k wolf marks for one set for the achievement. If you do the roulette each day, that would be about 9 days for one full set from only doing roulettes, and since the set can be used on multiple classes (Tanks/Healers/Mage DPS), you can get multiple achievements for it if you wanted to. Meaning if you literally did the bare minimum, you could get multiple sets, if not most, from the shop before early access starts for 5.0. Then there's during 5.0 when people will be using the PvP roulette stuff for bonus EXP, so it'd be pretty easy to get everything.