Boiled turkey hearts. It's inexpensive (although some months hard to get, so I try to stock up), healthy, and easy to make, just toss them into water and boil, drain, chop. You can optionally add seasoning to the water (garlic powder, ginger, whatever).
I also like string cheese, Enda loves jalapeno flavored, it's easy to cut off bit with your fingers.
I almost never buy anything marketed as treats/training treats, I do use the lamb lung bits, but those processed squishy liver scented things are just too expensive! I mean, it's usually $3.99 or what not for a bag half the size of what I normally go through in a one hour class with Enda! Yes, I do take out of her meals and replace with the training treats, but it's not like I even need to do that with her (actually, she chooses to do it on her own, my picky eater) she's so thin as it is.