Hi efg,
Welcome to the Mattress Forum! 
I personally know little to nothing about the Swiss or French market and the language barrier, distance, and different time zones along with my own time limitations makes research there much more difficult but the same basic information, steps, and guidelines in the mattress shopping tutorial would be the same in any country.
Just like in North America … I would focus more on materials and components than on brand names, avoid larger mainstream manufacturers or chain stores, and focus more on researching and finding smaller local or regional manufacturers that sell factory direct (or online) or through better stores that are more knowledgeable, experienced, transparent, and informed. They tend to be more responsive to their local reputation and customers’ needs than they are to higher profit margins along a longer supply chain, advertise less, and tend to use higher quality and more durable materials in their mattresses at each price point. They tend to “educate” their customers rather than simply try to “sell” them whatever they are willing to buy.
The only caveat is that in North America the foam density guidelines for polyfoam and memory foam that I would normally suggest are expressed in lbs/sq ft while in Europe they are often expressed in kg/sq meter so you can use the online density converter here to “translate” them. With latex it would be the same process of finding out the type and blend of the latex so you can make more meaningful comparisons with other mattresses.
The transparency of the retailers or manufacturers you are dealing with is always one of the most important criteria I look for so you can find out all the layers and components in a mattress and identify any lower quality materials or “weak links” that are in any mattress you are considering (see this article).
The same factors that are involved in the value of a mattress purchase in North America would also apply to any other country as well. The most important part of value is always comfort and PPP (Posture and alignment, Pressure relief, and Personal preferences) which is all about how well you will sleep on a mattress. Second is the quality and durability of the materials in the mattress which is all about how long you will sleep well. Third is how the mattress compares to your other finalists based on all the other parts of your personal value equation that are most important to you. There is more about the most important parts of the value of a mattress purchase in post #13 here.
While finding these can be somewhat of a challenge because they are often not as visible through the “noise” of advertising done by larger manufacturers and retailers … it is usually well worth the effort.
[quote]Otherwise the other possibility to consider would be to get a BB (or other) mattress and ship it abroad. I’m not sure how much this would cost, but I would be willing to do it if it’s the only way to guarantee a mattress of sufficient quality & value. I tend to buy a lot of well-reviewed U.S. products and ship it over here for that reason. Also being able to comparison shop in the States often lets me buy cheaper, offsetting the shipping cost, though usually this is for comparatively lighter items like electronics etc.
My main concern is that I’ve read that folks who didn’t unwrap their compressed mattress immediately had problems with the mattress not fully expanding (which seems a general issue with BB), so I’m worried the 1-2 weeks of compression while shipping might be fatal. Also I guess it would rule out any possibility of return since it probably wouldn’t be cost effective to ship it back to the U.S. (and re-ship replacement), not to mention the difficulty of packaging it up first.[/quote]
There would be no problem with compressing a mattress that uses good quality materials for a few weeks during shipping to Europe. BB did have some issues with a small number of their mattresses not expanding to full size but this wasn’t related to the time it was compressed and was related to the gluing and compression process itself and only applied to a very small percentage of their mattress that were made over a short period of time. It has also been resolved.
I don’t know which of the members are able to ship directly to Europe so you would need to email them and ask. You could also use a re-shipper but I don’t know which ones would be reliable or the costs involved.
There is more about the different ways to choose a suitable mattress (either locally or online) that is the best “match” for you in terms of PPP in post #2 here that can help you assess and minimize the risks of making a choice that doesn’t turn out as well as you hoped for once you actually sleep on your mattress. The most significant disadvantage of shipping a mattress to Europe is be that you would effectively lose the ability to exchange or return the mattress (or individual layers in a component mattress) just in case the choice you make doesn’t turn out as well as you hoped for and whether this would be a good idea would depend on your confidence in the suitability of the mattress, your risk tolerance, and on how it compares to the other local and online choices that are available to you that wouldn’t involve shipping overseas.
You would certainly have some good quality/value choices available to you in both countries but it may take a little bit of research to find them.
I’m looking forward to finding out what you end up deciding … and of course any comments or questions that I can help with along the way. I also hope you have the chance to let us know about some of your discoveries and of course if any of the members here have more knowledge of mattresses or manufacturers or any better choices that are available in France or Switzerland I’d welcome their input as well.
Phoenix