Closest alternative to Hypoallergenic Food

[Rockblind]

My BLM is always scratching, the vet has stated he has allergies?? We had blood work done for a thyroid which came back negative. We have changed his food to food without corn with no success. Now he has sugested we go with Hypoallergenic food, bought the first bag, whopping $72 tax in! for 26 lbs. Told the wife we will have to go cheaper, is there any alternatives oout there? Should I go brands that state good for skin conditions only? or stay with the Hypo type that states food allergies/skin conditions? The Hypo I bought was 1st choice brand, the vet was suggesting Hill's which is around the same price but less lbs. My first thought would be if i try the Hypo first and the scratching goes away, then try the type that is for skin conditions and if he's good on that stay that course if not go back to the Hypo. I was looking at the eukanuba naturally wild product??

Thanks,