Actually If I was using your formula, a +1 to perception would be always, resulting in 2x cost, so it would be 8. Because there is no conditions for it to be done. Just simply making the check, which could always happen.
And for the cosplayer - In a crowd of normal people, yes a cosplayer would be spotable. Same thing when you got a troll in a crowd of dwarves. Because they are the odd one out in the local immediate local area.
Now think of when someone dresses up like Naroto or Vash the Stampede and then try to find information on one particular one of those cosplayers. Surge III might not have the numbers of a full on metaype, but they're often less unique than those who are Surge II.