Doubling the order more than doubles the bill: 40 packs cost more than twice the 20 packs with 100 stickers, and the bigger listing never states its sticker count. One title says "Figurines", the other "Figures", and neither says how many come in a pack, so check the seller's page. The multi pack of 5 single packs (25 stickers) works out at the same 5 stickers a pack as the 20-pack listing, so it is a sensible trial run.
Next, decide whether you want an album to fill or a book that stands alone. The Official Netflix Sticker Album runs to 32 pages, but its title does not say how many stickers it holds or whether any are included, so ask the seller. Puffin's Official Sticker Book is titled as a book rather than an album. The Get Trend journaling book costs more, does not call itself official and, going by its title, is aimed at girls. No listing here gives an age.