Google offers a service called "Cloud Translation documentation" where the first .5 million characters are free and it is quite reasonable thereafter at $20 per million characters a month - https://cloud.google.com/translate/docs. In terms of it being "good" the Spanish-to-English comes in at approx 85% (which is close to human performance in a controlled test setting) but this may have improved in the last 2-3 years. They also provide api's etc so you can plug in your data in a number of ways.