For in-store pickup only and with stock varying by ZIP code, Kmart offers the Rock Tube Bluetooth Portable Sound System with Subwoofer, model no. CSR-E525, for $13. That's $37 off list and the lowest price we could find. It features an FM radio, up to four hour playtime, and support for USB, SD, and AUX inputs.
Of note, Shop Your Way Rewards members may be eligible for additional credits and discounts.