Not to shamelessly self promote, but the best way to buy/sell large amounts of BTC is directly, without going through an exchange/retail site. It is faster, cheaper and definitely a better customer experience. I've worked at two bitcoin exchanges so I know from experience. Now I am arranging private deals between a buyer and a seller. Here is the plug now though www.BitcoinCapitalPartners.com
FYI if you live in San Francisco and make less than 54k a year you can get Healthy San Francisco (http://www.healthysanfrancisco.org/). It can be free depending on how much you're making. When I had a startup I broke my arm and had to get surgery, it was only $100 bucks.