Thumb Score: +29

Elegoo via eBay has a promo, buy 3 get two free.

There is also a 20% eBay coupon: LABORDAY20

Add 5 filaments of your choice to cart from this link [ebay.com]
2 of the filament rolls will be automatically discounted at checkout
Apply 20% coupon LABORDAY20 at checkout
You can mix and match filaments, so pricing will vary depending on which filament you choose.