I had to stop using commercial dog treats recently. Even a half biscuit of some brands, and my golden retriever turns red. I went the simple route: dog biscuits made by the kibble company. They're the same price as the non-hypoallergenic ones, but without the dubious ingredients. I wouldn't eat them myself (they're a bit too crunchy) but the ingredients (with the exception of seaweed and one other thing, probably nettles) are all recognisable as things I personally have eaten at some point in the past. Thankfully they seem to be considered tasty. For variation, we also use the same brand but in cat kibble for clicker training. I'd recommend brands, but I suspect from the labels that some of mine are UK only.
Anything else we feed is human food carefully chosen (no beef, pork, gluten, chicken, what or anything artificial due to allergies). Basically, the dog eats better than me. I find human foods (cheese, lunch meats, etc) are often cheaper than dog treats. On a good day, I get 2,000 clicks from a £1 box of mild cheddar cheese.