I've been buying the Zuke's puppy treats and then cutting them in half. Treats are expensive - there is a recent thread here with instructions and recipes on making your own. I am trying one recipe this week - tuna fudge!
I was using regular puppy food for treats with potty training but there wasn't anything really special about them. When I switched to using the actual treats for treats, it was a bigger deal to get the treat after going potty. I had bought Wellness soft bites and tore them in fourths, but they are fairly rich. Brodie can handle them now as special treats, but when I started using them as potty treats, they gave him loose stools. Too much of a good thing. Hence we now reserve the Wellness for really special times like when the vet comes to visit.