Shipping heavy books overseas / Royal Mail M-bags

BountyHunter338

(please feel free to move this thread if this is not the best place for it)

I have done a search & found some threads posted on this subject in the past, but thought perhaps someone might have new thoughts to add, especially as the number of knowledgeable ebay sellers on this site has increased.

I need to post a large quantity of books to the US as cheaply as possible (speed is not a concern). The weight of the parcel will be between 15-25kg.

In Germany, Italy, and the US, large shipments of printed materials can be sent cheaply via M-bag (also called "media mail"). Even though I found some past threads on MSE stating that M-bags are solely an American thing (e.g. http://forums.moneysavingexpert.com/showthread.html?t=415895 ), this service appears to be available through Royal Mail as well.
See the bottom of this page: http://www.royalmail.com/portal/rm/content1?mediaId=31000679&catId=14800159
And the top of this one: http://www.royalmail.com/portal/rm/content3?mediaId=53800694&catId=600110

The problem is that it's a bit vague as to whether personal customers can use Royal Mail M-bags, or whether this is a service requiring a business account. I don't intend to do this more than once or twice, so setting up a costly account is not desirable. Does anyone have experience using Royal Mail M-bags, or any other ideas for sending these books cheaply overseas?

I've sent an inquiry via email to Royal Mail but haven't yet heard from them. My local Post Office always seems frenzied/mad so I'd rather not go in person to ask if I can find an answer elsewhere.

Many thanks in advance. I love being able to consult experts on MSE!