I have only bought a mystery box one time in my life and it sucked, but
graveyardmall is offering money back guarantee with free return shipping if
not completely satisfied. So for all those people that always wanted to
try a mystery box but didn't want to take the chance of getting a bunch of
crap here is your no risk chance.
Link: http://www.graveyardmall.com/gumybox.html
You can also let them know what you like so they have an idea what to put in
the box.