I am transcribing a Spanish/English book. The symbol for euros is used and there is not a symbol equivalent in Braille. I have looked in the BF and in the Spanish Interim Manual. Here is and example of one of the ways it is used in the textbook:
Imagine you have 5.75€ (euros) to spend on fruit at the local fruit stand (la fruteria)
There IS a braille symbol for euro and it may be found in the 2007 BANA Update on page L7. It is listed as an additional symbol and is used in all transcriptions, like the dollar sign, trademark, percent sign,etc. It is [braille]@e (dot 4e) By all means, use it in a foreign language transcription as you would any other symbol of this type.