As one of its daily deals, Groupon offers the Kagan AutoTunes Cup Holder Speaker
, model no. ASI8722, for $18
with free shipping
. That's the lowest total price we could find by $18. This portable speaker is designed to fit into a cup holder and features a built-in adapter, two 1.5" full-range drivers, and more. It's compatible with most MP3 players and phones and requires four AA batteries (not included). Offer ends January 11.