just because other people (like me) can't stop brewing more than they can consume doesn't mean you'll fall prey.
my biggest problem is all my friends moved 520 miles away (work related) and swmbo doesn't drink much beer. so for one guy trying not to gain 5lbs a month, 2 cases takes a bit of time to drain.
get the 5 gallon kit. you can always pickup a 3gallon carboy later, and do smaller batches. its less payoff for the work, but if you're like me and just enjoy the brewing process, you don't mind the smaller all grain, stove top batches. its cheaper for experimenting with different recipes at least.
Primary: English Mild
On tap: Pale Ale, Lancelot's Wheat, English Brown Ale, Steam Beer, HoovNuts IPA
Bottled: MOAM, Braggot, Raspberry Melomel, Merlot, Apfelwein, Pyment, Sweet mead, Cabernet
Gal in 2009: 27, Gal in 2010: 34, Gal in 2011: 13, Gal in 2012: 10