What has to be taken into account about top DJs, is that a lot of their revenue comes from royalties from the records that they have made in the past, especially names like Carl Cox, Sasha, Oakenfold etc. It's not all DJing fees.
I remember in the 90s, Judge Jules was paid 250K to play for 2 hours in Sheffield, so there are a lot of big earners out there. Pete Tong cost £1200 when I booked him to play a gig for me in 1993, so that would be what? 8K'ish now, but well worth it, he packed the 1800 capacity club and there were 400 queuing to get in, he also plugged the gig on Radio 1 for 2 weeks.