On the Post.NL website, it says that
What does it cost?
Registered Mail is available from just 8.45 euros.
So your friend is correct. However, it also says:
Make sure your item meets the size and weight requirements:
Max. size: 38 x 26.5 x 3.2 cm
Min. size: 14 x 9 cm
Max. weight: 2 kg
and these are the dimensions of a sizable, hefty ...
According to US Customs and Border Protection (CBP), you need to fill out form 6059B which is available here. It's a fillable PDF form Note: I couldn't open the form with my version of Acrobat Reader but I don't have the latest version.
Elsewhere, it says that you must have complete lists of both household effects like furniture, artwork, dishes, etc. and ...
If we mouse-over the question-mark links, or read this form, this is what each of the extracts contains:
Extract with citizen service number: Extract with your name, date of birth, place of birth, country of birth, gender, nationality, citizen service number (BSN), current address.
Extract with historical addresses: Extract with your name, date of birth, ...