Wow, you're pretty well prepared. I'm not sure what a grain father is but if you plan on doing full-size boils for 5.5 gallon batches instead of topping off the carboy with water post boil you need at least an 8 gallon kettle in my experience. Also, I prefer to have Powdered Brewery Wash (PBW) for cleaning and Star San for sanitizing. With these you will rarely need a carboy brush, but I'd still have one. A bottling tree is convenient but not a necessity. Make sure you have a hydrometer jar. A wine thief is handy for taking samples for gravity readings. I really recommend a cheap rope bucket to use as a swamp cooler for maintaining constant fermentation temperatures. I also prefer a good digital thermometer. I have one made by CDN.http://www.cdnw.com/product/proaccurate
As far as where to get the equipment I'd shop around. For brewing-specific equipment I recommend a local homebrew shop. Stainless steel is nice but I use aluminum kettles. I found good deals at the local Bass Pro Shop and on Amazon.com. Unless you have a good stove (or to avoid ruining a good one) I would recommend a burner i.e. turkey fryer burner. The local Bass Pro often has burners with 8 gallon stockpots for $70.
No matter what equipment you use that is not nearly important as sound cleaning and sanitizing, pitching the proper amount of healthy yeast, controlling your fermentation temperature and keeping recipes simple at first.
Welcome to the obsession.