This is what most etiquette books/ websites say:
DJ - If your DJ owns the company then the tip is optional but if the DJ is an employee $50-100.00. If you have 2 DJs (DJ & MC), give each person $50.00 in separate envelopes. When your guests rave about your reception later, it's the DJ that had everything to do with the fun.
We have the same philosophy here with our employee djs. Also we let the djs take overtime directly and we dont cut in on it because it the guests had such a great time the host wants to buy more time its a total reflection of the dj
