Yep, you can go anywhere and pay full price for a gas can. In fact, you can often get a better price than HF even with the 20% coupon.
RK also has a 5G for $12, though it's a different brand.
https://www.ruralking.com/catalog/product/view/id/36818
People make the mistake thinking that getting 20% off something has to be the best deal. A few years ago I went to HF to look at their panel lift...Drove right across the street to compare it to Menards. Theirs was on sale just like HF but the Menards was like $16 less even after adding the HF 20% coupon. The lifts were also identical, I took pics of every little detail for comparison.