I feed PreMade raw, so my situation is a bit different. But I'm so excited for you!
There are some calculations online here and there (I'll have to look) that compare costs. Premade is *not* cheaper, in my opinion. But Prey Model definietly can be - when you're looking at .59 per pound (where as Premade is $3-5+ per pound). I know Nadia (RawFedYorkieLuv) looks for $1 per pound and under and she does not buy organic meats. You feed a LOT less volume in raw, as compared to other diets. When you say "cheaper" - do you mean cheaper than kibble, or homecooked, or something different? It's not cheaper than kibble, imo. For me, it is cheaper than cooking (which I used to do).