Well, just a week later I got the package:
Excited, I just took a picture of it and I proceeded opening it.
Just to find inside everything from my order. The soekris stuff, the rubber duck antennas, the usb-to-serial adapter, the null-modem cable and the t-shirts. Everything OK.
Now I only have to find some time to install OpenBSD in one of the net5501-70 to use it as my primary AP/Firewall/whatever device here, and then I'll install OpenBSD, FreeBSD and Linux in the net5501-60, just for testing purposes of the three operating systems.
So, more to come about this soekris topic, meanwhile relax with some pics of them: