I almost imported a horse from Europe last year. Call your local airport authority and large animal vet clinic. They will be able to guide to all the companies that do transport.
The price quotes all have to do with the size of the box you get. If you are moving a couple horses, it will cost relatively the same as if you move just the one. You also have to take into consideration the cost of quarantine for that 30-60 days(depending on what the laws are where you move to), as well as vet care because the horses will have to undergo regular blood, urine and orrifice swabs to test for disease and parasites.
By the time it was all said and done it was going to cost around 8,000 for the move and all the vet care.
Keep in mind to depending on what the laws are where you move the horses to, if they were to test positive for certain parasite, the quarantine area will chip the horses right back where they came from, no questions asked. It shouldn't be so much of an issue if they are coming from here to Europe. Been a big issue with European horses to Canada/US.