As one of its daily deals, 13 Deals offers this Solar Light Up Mason Jar for $16.99 with free shipping. That's the lowest total price we could find for such a jar by $13. It measures 4" x 7" and features warm and cool selectable light.
Of note, you can buy two for $24.98 with free shipping.
Update: As a reader has noted, the price for the single item drops to $14.99 in-cart. The price comparison information has been corrected to reflect this change.