Walmart offers the Arrow Rivet Fastener 120-Pack for $6.27. (Amazon charges about the same price with free shipping for Prime members.) Opt for in-store pickup to avoid the $5.99 shipping fee. That's the lowest price we could find by $2. It includes 60 aluminum rivets and 60 steel rivets in 3mm, 6mm, and 12mm sizes.

>Update:Pickup is available again at Walmart.

Update 2: Headlines have been corrected to reflect that this pack does not include a riveter; we apologize for the mix-up.