This is a really well thought out idea. I will ask some busy employee to stay on the phone for a while and list the prices for everything in their freezer. Great idea!
That was a really well thought out reply to a good idea. ...oh wait, my mistake, it was a a poorly thought out, quick to dismiss, snide, sarcastic response to a very good idea.
I'm assuming that you've never worked in retail or customer service. Retail stores are in the business of selling things to customers to make a profit. If a customer has a question which when answered may lead to a sale, or in the case of pet food, potential repeated sales, it is beneficial to them to answer your question, whether over the phone, or in person. Those $5 sales based on good customer service add up to a ton of money when you consider all the different people buying them, and all the different locations getting those sales, especially if they're taking them from a competing pet store. These sales often lead to the sales of other items as well, bringing in even more money.
If your issue is not wanting to bother an employee to do the job that they are paid and trained to do, just go to each store and price them yourself. No one here, unless they live in your area and shop at the same locations, will be able to give you accurate prices for the items at your local chain stores. Even the websites for both companies specifically state that in-store prices may differ.
We've offered you options and tried to help answer your question as best we can (considering you want an answer that's impossible for anyone here to give accurately), and you've chosen to spit in the faces of those kind enough to try and help. I'm curious as to just how long you expect people to continue bothering to offer help if that's how you're going to treat them when they do. Now if you'll excuse me, I need to go reply to the "Does This Annoy You" thread...