If you choose Valandre, I think Freya (or Shocking Blue) is the best for your trip ideas. I have Freya, and it has been more than sufficient on Aconcagua and in the Pamirs. For the Alps (whatever season) I use ME's Snowline, which has -17°C EU lower comfort limit rating; this bag was also fine for Elbrus.

In Europe it is very difficult to find the similar class US made sleeping bags. About the price difference, take eg Feathered Friends. If you are looking a -30°C (-22°F) sleeping bag (like Freya), then the FF equivalent will cost you roughly around 650 USD, which is about 450 EUR. You win (roughly) 79 euro. Well, it's worth it if you buy the bag in the States. Even if you can find it in Europe, I doubt whether the price will be lower, if at all. The US products tend to have the same prices in Europe as in the States, but then in euro units.