I can translate without any kind of problem from English into Spanish and from Spanish into English.
The cost of a translation depends of the lenght of the document; meaning how many words does it have. A basic translation cost is 0.03 per words. On the other hand, if it's a complicated transcription, (Medical, legal, etcetera) it has a little extra cost since it includes investigating all the necessary terms related to the project.
Anyway, depending on the type of project the total price might be negotiable.