If by $200, you mean a limo is taking you and friends to the ceremony, then afterwards, the limo is transporting you from party to party with your friends while you all celebrate your graduation (complete with a stocked bar in the limo), then it's a bargain!
If by $200, you mean a limo picks you up at your apt/house/dwelling, transports you to graduation and drops you off, then... are you that foolish that you have to ask that question??
I assume you're somewhere in between... use your best judgement.