I'd say the Sanwa japanese sticks are gonna be your best bet. They are gonna be hard to get anywhere except for japan though, or if you know someone that works for like lets say Capcom *Allah01 cough* your next best bet is the J-stiks from the Ultimarc website,
www.ultimarc.com they use basically the same parts as the sanwa, and I believe have just as short throw, the springs are also super light on them. If your looking for buttons that match, the Competition Buttons are the next closest thing to the sanwa buttons. Also, if you do somehow get ahold of Sanwa buttons, they are a biznatch to mount because they are so short, they are meant for metal/plexiglass control panels like the japanese ones. The only place I know of to get competition pushbuttons is straight from
www.happcontrols.com since
www.therealbobroberts.com wont sell em, I emailed him and he told me he doesnt stock em cause he says they feel like crap, which for old school they sorta do. For fighters they are great though, although there's NOTHING wrong with the horizontal pushbuttons, I love the ones on my cabinet. light springs, easy and fast repushing, very short distance for pushing. great stuff.
-Any reason you want to know of a short joystick?