So if your company is not doing the fermenting and you're just buying finished beer, then you're not a brewer you're a wholesaler.
Brewing has brutal economies of scale, so if you're buying a few 100kgs of ingredients you will buy them at much greater cost than somebody buying hundreds of tonnes. Also don't expect to be able to rock up and just buy 10kg of Galaxy and other rare hops, you usually need to contract then - although the current collapse of the brewing economy may mean all sorts of rarities becoming available that were contracted by bankrupt breweries.
The other problem with cuckoo brewing is that your host may not want "exotic" yeast and bacteria near their brewery.
Actually the process is documented in pretty exhaustive detail in Ted Bruning's book - if you're serious about doing this then you need to read it.