Hello Piotr, Simply go to the USPS website and click on "Quick Tools".
Here click on "calculate shipping". Enter information about package
size and weight. You can now see the cost of every option including
Media Mail.

For very light packages, there is often not much savings between
Media Mail and First Class mail service. Media Mail cannot be used
for international shipping.

Regards,

Jim Quashnock
Wichita Falls, Texas