Depends what your purpose is. If you already know what the document says and just need to get the information in front of the court but aren't too concerned about 100% accuracy, just go for the cheapest certified translator you can find. I've used Donnelly Language Solutions and TransPerfect. Both are good.
Also, keep in mind that there is no official standard for translators. That means that even a translation prepared by a non-certified translator will generally be accepted by a court as long as it is accompanied by an affidavit stating that the translator is fluent in both language.
