Home Depot has a nice price on inexpensive light duty extension cords plus free shipping to store for pickup:
3-Pack HDX 50 ft. 16/3 Light-Duty Indoor/Outdoor Extension Cord $7.14
https://www.homedepot.c
6-Pack HDX 50 ft. 16/3 Light-Duty Indoor/Outdoor Extension Cord $14.28
https://www.homedepot.c
Note: works out to $2.38 per extension cord.