Personally I don't like DJ'ing weddings but I often get asked to DJ the after party. Overall I seem to get questioned frequently on how much DJ services for a wedding cost.
If you live in a local non-metropolitan area, you should expect a DJ to cost around $500-$700 for the event.
If you live in a more populated area (San Francisco, New York, Los Angeles, etc) you can expect an experienced DJ to cost $1500-$2500.
Here is the pricing I use personally.
1. $1500 Flat for 6-8 hours, one night of lodging comp'd (if not within 100 miles of San Francisco). This flat fee includes Equipment & Speakers.
2. $500 Flat if 3-4 hour after party. Add on another $200 for Equipment and Speakers.
Either-way I hope this is a good guideline. Feel free to reach out email@example.com