Our local Association buys in bulk and we pay 80p ltr for *ambrosia* . Sugar at the local cash and carry is just 70p kilo.
I use sugar for the bulk of feeding both winter and a bit of spring/new colony feeding, but I do buy some invert syrup as it seems to store better and I like having some on tap for emergencies or small amounts, so I don't have to always mix it up.
The sugar syrup is storing better than it used to now I put some thymol in the winter feed.
No doubt in my mind that the sugar syrup is still half the price, but many people around me are convinced its not, talking about about how much you need to create a lb of stores etc as well as lots of dubious "its better for the bees" or they don't have to evaporate it.
It does sound a lot like marketing speak and deliberate confusing, mixing up volume, weight, metric, imperial etc to throw you off the scent. A local bee farmer spent 25mins recalculating his figures on his phone calculator to try and convince me it was CHEAPER than using sugar.