$8.49 or $0.01689 ea https://www.amazon.com/gp/product/B09GWBJ97Y Oxford Index Cards, 500 Pack, 4x6 Index Cards, Blank on Both Sides, White, 5 Packs of 100 Shrink Wrapped Cards (40177)

$20.89 or $0.04178 ea https://www.amazon.com/gp/product/B08TRPZK1B Columbian #10 Windowless Envelopes, SimplySafe Tamper Evident, Security Tint, Peel and Seal Closure White, 4-1/8 x 9-1/2, 500/Box (COLO180)

You can probably find them for $0.02/ea for a box of 50 at the dollar store, but you may have to seal the envelope manually. The link I provided is peel & seal.

$54.57 or $0.5457 ea https://www.amazon.com/2022-Roll-Dispenser-Contains-Forever-Postage/dp/B0B9L5NLZ2/

You can sometimes find in bigger lots for $0.10 or more off. Tanga also has discounts sometimes. https://buydiscountstamps.com/product-category/forever-stamps/

Pens, you figure out. Get a box of 10 BIC pens with black/blue stripe cushion at the bottom for $2.50 a box. You can't use them for black ink for Pulsz, so you might want to get the blue if you're writing it to more than one online casino.