Quite steady priced around here too at from $2.80/gal to $3.09/gal at the pump depending on which station. Buying it in 2.5 gal containers simply means you are paying dearly for the container it's in. Keep the containers! Several bucks each time one's bought! When near a pump, refilling one or two of those DEF containers lets you take advantage of the lower price big time. 2.5 gallons lasts a lot of miles so it's not often you'd have to refill it. Also when there, of course fill the truck's reservior and you're good for 10,000+ miles before needing more. Works out to about 1/10 of a penny per mile driven. Just the normal evaporation of the costly diesel fuel itself costs you more than that! How much cheaper could it get as the DEF system in return gets you 1-3 more mpg's!
Remember that having an empty container or two means you had already paid for it once, why again?