It DOES seem high for 250 gallons of storage. Nice that it has a small footprint, but a big price tag for sure. If you want to store around 300 gallons, or in increments of 300 gallons, I would suggest you watch Craig's List for something like this.
I've seen these for $50 to $100. Try for one that had soda syrup in it, not cooking oil. Easier to clean.