1999 996 C4 clutch question

Vehicle Information: Model: 996 C4; Year: 1999; Body Type: Coupe; Total Mileage: 49,500;

i have a ''99 c4. i''ve been noticing, what i guess is slipping, upon acceleration in the 2,000-4,000 rpm range. i''m assuming i need a clutch and/or flywheel. can you enlighten me a little on symptons of a clutch/fly wheel problem or did i answer my own question? can you have a problem with just one and not the other or do both parts usually need to be replaced? what kind of ballpark cost am i looking at for these repairs at my local dealer?thank you