Advice on shipping a DCM overseas?  

claus, this may not be the...
claus, this may not be the answer you are looking for but I think you will get the best deal on shipping rates from the major freight forwarders. That means having your seller ship it to a U.S. address, from which the forwarder takes over. You will find my experiences of that procedure in the linked thread. If time isn't an issue, I would pick a forwarder that offers sea freight. It makes a big difference on shipping cost.
http://www.designaddict.com/design_addict/forums/index.cfm/fuseaction/th...

Thanks Gustaf! That might...
Thanks Gustaf! That might just be what I'm looking for. The rates seem OK (I looked at Bongo) and especially with larger items USPS or UPS are just too expensive even if the seller would offer that option. So maybe I'll give this option a try...

Just has to fit
Into a package that is
Some countries have a smaller size limit.

woodywood, what type of...
woodywood, what type of shipping does that limit apply to?
claus, a word of caution, though I am sure you know this already: all shipping rates refer to dimensional weight.
This is why I prefer sea freight for bulky items.
http://www.bongous.com/mail_forwarding_faq.php#q17

US Postal Service
Priority Mail International
"6-10 days" according to USPS website
www.usps.org

Gustaf is right: It's about...
Gustaf is right: It's about dimensional weight. And that's why shipping with USPS (or any other airmail service) is either too expensive or impossible for larger items.
Sea freight is quite slow, but still the way to go here I guess.
Bongo seems quite trustable, I've seen some forwarding services which seemed dubious or got bad reviews on the net. Maybe Bongo's worth a try.

Disassemble
The frame should be able to fit into a box that meets USPS size limits. The seat and back rest can be shipped in another box.