I remember way back that you could get Shonen Jump at places like Borders and Barns & Nobel in the magazine section (I think other comics were there too). It's been ages since I've gone to Barns & Nobel because it's a pain to get to, so I have no idea if they still sell them.
Anyway, they also have other anime and manga items around where the manga volumes are sold. I got a leaf headband and a kunai holder there.
(This was back in 2007)
I think you can get a subscription online for it and maybe on some site that actually will send you one either weekly or monthly. Also check Amazon!