I would start with at a minimum of a round 10 gallon beverage mash tun, 10 gallon boil pot and 2 plastic buckets to collect the runnings. Others would say, a huge rectangle cooler.
You will know after a while if you want to 'build' something, which it sounds like you would.
Anyway, you can see my progression of equipment into AG in my Flickr link below. Early photos from 10/2010 - 12/2010 show a change in a burner and a MLT. I also went from a stainless conical to a plastic bucket.
Now I'm using a keggle and pressure fermenting in a corny... Things change... change is a constant.