Amazon has the 3-pack Sengled Dusk-to-Dawn A19 1200-Luumen LED Sensor Outdoor Light Bulbs (5000K Daylight, 75 Watt Equivalent) on sale for $9.59 with free shipping on $35+ or with Prime. A 6-pack of non DtD 800-Lumen bulbs is also on sale for $16. 

• 10.5W actual usage, 25000 hour lifetime. Automatically turns on at dusk and off at dawn.