At this stage I'm in limbo between DHL and UPS. The former is a bit cheaper the latter is a bit more reliant.
For the numbers you can calculate it online on their websites, weight per module: ~500g.
For bigger numbers of boards I'll ship them in multiple packages.
You might check out this test about german shipment providers:
http://www.computerbild.de/artikel/cb-Tests-Sicherheit-Paketdienste-Test-DHL-Hermes-DPD-GLS-6816000.htmlThey shipped measuring devices to check how they handle the packages. DHL won overall and was the fastest.