Complex sentence: Mobile DJs who once were averaging $350--500 per four hour event in the 1970s, now on a national average for a wedding can command anywhere from $800--2,500 per event, with the national average being around $1,038 for a wedding reception.
Split into simpler sentences: Mobile DJs who once were averaging $350--500 per four hour event in the 1970s, now on a national average for a wedding can command anywhere from $800--2,500 event. With the national average being around $1,038 for a wedding reception.