Acceleration Module ?

Hello !
I just had a Diagnostic done on my 94 E420 and was told I need an accelertation module? $1100.00 installed ! but they also said if that's not it it would be another thing that cost $2500.00 ? not sure what that part was though? It was done at European MotorCars of Des Moines,Iowa. Can i get this part cheaper somewhere else? and how can they not be sure which one it is with all of that Diagnostic Computer junk they have? I can be reached at PerksBenz@webtv.net as well ! that's at my apartment ! Thanks a Million !
Bob

I found my papers and it says the parts are an Injection Module and or an M16 Throttle Acuater? If that helps any ?
Thanks again !
Bob