Good sale on these at Lehmans. https://www.lehmans.com/product/diet...t-oil-lantern/
I got 2 last night for $9.99 with shipping $29.30 so about $15 each to your door. Only the blue ones and they are now out of stock but you can backorder them. Several others are on sale, too. For this price, I don't know how anyone can resist a backup light source.
As an aside, I'm trying a Mars no. 78 I picked up at a local lamp shop for $9.99 on sale and might go get another of the smaller one. I used lamp oil but now am using Extra Virgin Olive Oil to see how it runs. Sputters a little but runs ok on it. Good for a pinch.