Williams Sounds is not very good equipment. You should be able to get something from Audio-Technica, Shure, or maybe even Sennheiser for $2300. Although, this depends on how much of the mixing equipment you are expected to buy. Check out
Markertek or
B&H for good prices on quality audio gear.
Basically, you need two wireless mics on the speaker--one going to main mix and one to a separate channel on the board dedicated to a sub-out for the translation person*--and then a mic on the translator going to a channel on the board with another separate, dedicated sub-out for the amp that feeds the translator headsets. As the translator, you hear the speaker(s) through headphones and then speak the translated words into the mic that gets sent just to those folks listening on the translation headsets. Everyone else in the audience just gets the sounds from the house PA system.
*Depending on the type of mixing board in the venue they might get away with one mic if it can be assigned pre-mix to a sub-out and then get routed to the main mix. I know certain Mackie boards can do this; Yamaha boards probably can as well.
NOTE: If any of this terminology is confusing to you, you need to learn all about audio mixing because that knowledge will be essential when you go out on a job. (I am assuming you are a freelancer who will go to places to do simultaneous translation work.)