Aircraft brokers, on average take a 1 % commission (realistically), depending on the size and marketability of the aircraft.

So suppose that you’re selling this aircraft for example,

a Dassault Falcon 50, Year 1994, TTAF(Total Time Airframe) 6,855 hrs. -it was listed last year at $2.5 MM. Full details here. Comission: $25,000.

Note: Video below may be a different aircraft.

For most important considerations to aircraft purchases,  I recommend reading NetJets Buyers Guide

Arguably the most qualified and reputable brokers  are NARA (National Aircraft Resale Association) certified and adhere to NARA’s Code of Ethics.