Typical deal scout commission

Hello all,

So we are working with a few deal scouts that introduce us to potential businesses to buy and are paid purely on commission. Sometimes they send us platform businesses and sometimes, add-ons. Different people propose different commissions. Does anyone know of anything that's standard? Maybe Lehman for platform targets and 1-1.5% for add-ons? When negotiating commissions would like to have something that I can cite as standard.