Large MFR - what is a reasonable commission for buyer?

[Charlie MacPherson]

So as to avoid price-fixing charges, I'm looking for an average range - not a precise number, or a suggestion as to what all agents should charge.  Here's the story.

I've been contacted by a buyer who represents a large investors group.  They're looking for 100+ units with some other specific criteria.

I've done quite a bit of digging and found a good candidate property at $15M, but as is apparently common in CRE, there is no commission offered to the buyer's agent by the seller. That means that I need to collect a fee from the buyer.

My problem is that my experience is in SFR and smaller MFR where a buyer's commission is always stated. I have no idea what to ask.

Can you buyers or brokers share a range of commission rates or fixed fees that you've seen in the real world?