As your pm box is full again ->
There you go:
http://pe.usps.com/cpim/ftp/manuals/dmm300/Notice123.pdf
I never use their online calculator as it is kinda not telling you every option, especially the cheaper ones.
The pdf is the price list for shipping stuff international.
There you can go to first class mail
international - packages - Austria is price group 3-5;
Shipping costs 27,30 up to 56 ounces
28,87 up to 60 ounces
etc.
Important is only that the package has a length
of !max! 24 inches and
a !max! combined length, width,depth of 36 inches.
I think if your package fits the SNES tightly it shouldn't be bigger than that right?
Just tell at the counter that yopu want to ship your
small package with first class mail international.