What distance do you need it to cover? Is a range of 150 feet (from the interpreter to the furthest member of the audience) adequate? If so, your most cost effective solution is a Portable System.
If you need more than 150 feet, you will need to go with a semi-portable system. You will lose some portability, but it will still be easy to set up and take down. The range will increase to around 1000 feet as long as there are no obstacles.