ECO-WORTHY US via Amazon [amazon.com] has ECO-WORTHY 10W Solar Car Battery Charger Maintainer on sale for $42.99 - 50% off when you visit the promo code page to activate [amazon.com] (or apply code VYJGUJUI at checkout) = $21.49. Shipping is free.

Note: Amazon promo codes don't always apply seamlessly. If you run into this issue, refresh the page, re-enter the code, or revisit the cart page.