Yeti via eBay offers its Yeti Rambler 20-oz. Vacuum-Insulated Tumbler in Stainless Steel for $24.99 with free shipping. That's the lowest price we could find for a comparable Yeti tumbler by $5, although we saw it for $5 less on Black Friday. It features double-wall vacuum insulation and a clear lid.
These freebies are available to anyone with an internet connection — including those without an Amazon Prime membership.