Walmart offers the Nerf N-Strike Elite 250 Dart Pack for $11.98. Opt for in-store pickup to dodge the $5.99 shipping fee. That's the lowest price we could find by around $18, although we saw them for $2 less in our December mention. They're compatible with Nerf N-Strike Elite blasters.
If you have or expect to have a modest retirement income, you may want to avoid spending your golden years here.