I'm currently feeding my two boxer mixes the Natural Balance brand. It's great, but it costs $35 a bag. Eek! Due to the tightening of my economy, I need to switch to something less expensive. Any tips? My dad suggested looking at the Sam's Club premium brand. He also mentioned Purina One. They've eaten that before and done okay on it. I just need something that is nutritionally balanced and good for them. I don't know that the all veggie based products are. Any thoughts?