Our ages 10+ tickets were $31.90 w/tax each and our ages 3-9 were 26.58w/tax each plus $3 shipping and handling.
The paper that came with the tickets had a few guidlines for the costumes such as: do not have costumes that obstruct the guests view, affect their ability to get on/off rides and transportation, drag on the ground, contain sharp or pointd objects that could hurt another guest, are offensive to other guests, or have pieces tha resemeble weapons.
Check out this web page with info about MNSSHP,
http://wdwig.com/mnssh.htm
It took me awhile to justify spending the extra money, as we are going to have ultimate park hopper tickets for our week. But, my DH actually said to "just do it, it sounds like fun" and he was the one that came up with the idea for the costumes for our three sons!
Hmm, maybe there is hope yet for my non-Disney loving DH.