I'm from Australia , Standard international shipping would be Airmail.
To ship the book with that weight & size from Australia to Germany, it would be sent via Airmail as a parcel & a parcel with the weight of 4.2 pound(1.9 kilograms) would cost excactly $64.90AUD.Here is the graph for such delivery from www.auspost.com -
Destination Country: GERMANY
Location: Zone D
Parcel Weight: 1.75kg to 2kg
ECI Parcel Weight: between 1kg and 2kg
Details on size restrictions on parcels
Select Service Price Maximum Weight Notes
ECI Merchandise $79.00 20kg 1
ECI Documents $71.00 20kg 1
Express Post International $70.10 20kg 1
Registered International $70.10 2kg
Air mail $64.90 20kg
Sea mail $34.80 20kg
I had the same problem today, i sent a beastman figure & charged $11.00AUD, when i shipped today at the post office the actual shipping was $27.00AUD, i ripped myself off $16.00AUD but that was my fault.
Hope this helps!!
EDIT- sorry i thought it was $69.00, $89.00 is a little to much unless it is sent via Courier, READ Lorde Trooper Below