Correct Amount to Pay Friendor Serving as the Reception Mc/dj?

Suggestions please on a respectful cash amount to give a friend who has agreed to act as the MC/DJ for our wedding reception? We have a playlist already made up, and the venue has a wireless microphone and sound system she can use. It would involve her serving as the MC/DJ at the reception for 7 hours. She is also included as a guest at the reception with a “plus one.”
We would like to give her a generous amount for doing us this favor, but we are also on a very tight budget. Any advice appreciated- please help! Thank you!