I agree that if you can you should hire a dj. If budget is an issue, here are some tips to help:
a. Ask someone to manage the iPod or iPhone or laptop- perhaps you have a friend who prides himself/herself about music
b. Check out Pandora stations, Spotify, Songza for playlists
c. Ask someone to head the party fun. Get your most outgoing or funniest friend.
If you can then, take a chance with an up and comer dj. The rate might be reasonable. If you can splurge, splurge on a dj and a band!