Zycylight via Amazon offers its Zycylight 4-watt Dimmable LED Edison Light Bulb 4-Pack in Soft White for $21.99 $20.99. Coupon code "T3CJSZZM" cuts it to $15.39 $14.69. With free shipping for Prime members, that's $7 off and the lowest price we could find. Deal ends July 31.

A close price: Boshen-2013 via eBay has them for $15.98 with free shipping.