I've been organizing regular trips to Verge recently and I collect deposit of $60/px but most time the actual amount is less than that I'll do refund. It's not unreasonable in my opinion that the organizer gets a markup of $5 from each of the participant for a small room or medium package (never organize large room before and probably won't).
Reasons being:
1) If one of the bro suddenly fly aeroplane at the 11th hour, the organizer would have to bear the additional costs if he can't find replacement (might be partially covered by the deposit).
2) And if any bro MIA (not just new participant, some regulars can pull this stunt too) during the session and he has sat with 2-4 gals, who's going to bear the costs? The gals are here to earn a living and as the organizer, you will have to bear the costs and give a token sum to the gals and in this case, you have to give about $30 to each gal (based on Verge gal tips of $50), which means min. of $60 out of your own pocket (these unsteady dudes usually sit 3-4 gals). Some bros might disagree on paying tips to these gals but my take is that they have provided a service and we have to pay for it and this is the risk that organizers have to bear.
So the markup of $5-$10 is just basic risk management and i hope bros can understand that. I've encounter bros who niggle with me coz they have to pay $5-$10 more and you guess it, I've told them not to join my outing in the future please.
I've no interest to make $$$ out from organizing outings but a small markup above the shared cost price is just to safeguard myself against the unsteady dudes who should be ashamed of themselves!