4 hours of DJing for your event.
Just because the DJ is cheap doesn't mean they are the DJ right for you. Remember this is your special day, (If its a wedding DJ) you have spent money on a beautiful dress, Bridesmaids, hair, catering, cake, honey moon and more.
So when asking a DJ for a quote
$200 – $300 Typically is a beginner DJ, most likely a part-time hobbyist. They wont have a huge song list and their gear maybe old-second hand gear or a small rig as they can't afford the really great expensive gear and lighting. They wont have the years of experience behind them so wont know how to read the crowd or know the correct songs to play next.
$400 – $600 A lot More experienced than the beginners, most likely a part-time DJ, They would have been playing for years and be experienced in reading the crowd, plus have a great selection of music, know how to keep the party upbeat and dancing. Would have professional gear and lighting and be able to work with you to ensure the day goes to plan with no hitches.
$1,000 – $2,500 Most experienced, professionally trained, full-time DJ. May offer digital videos and photos, possibly include photo booth. Probably an established business that hire DJ's out so your paying a middle man. Now you should base your budget on what kind of experience you want at your wedding reception.