$450 dude is a good price on a DJ. I dont recommending skimping on the DJ at all. I've seen people pay $900 for shit DJs who sit on their laptops and play songs off of ITunes. I mean, it seems these days that a lot of DJs can get away without knowing how to DJ.
My advice is that if you want a quality DJ (Think, if you want dancing at your party, you want good music and you want good transitions so that you can keep on dancing), $450 can get you a good DJ. No self-respecting GOOD DJ will try to do a gig for less than $400.
But it is YOUR party. If you just need the DJ to do mic system, speakers and play occasional songs, then sure look for a cheaper DJ. But, I've seen people do grad parties with shit DJs and they've regretted it.