Walmart offers the Wonder Loom Rubber Band Bracelet Kit
, model no. US7270, for $12.88
. Choose Site-to-Store pickup
to dodge the $4.97 shipping fee. That's $4 off list and the lowest total price we could find. (Several Amazon 3rd party merchants charge close to $20 with limited stock on hand.) It includes 600 latex-free rubber bands and 24 "C" clips.
Depending on your area, this item will be guaranteed for Christmas via pickup.