I really don't think that's an unreasonable amount. Most people are renting this equipment for professional use and should easily be able to put that money down.

The reason I'd rent such equipment would be that I couldn't afford to own it. I would not handle it uninsured, of course, but I'd likely not pay to insure it against it getting stolen from me. That risk I'd eat and compensate with suitable security measures.

But putting those charges on your card within your credit limit and credit period doesn't cost much.

Can't afford would mean needing insurance, or selling/pawning property. Proper vetting enables you to use the threat of criminal prosecution and civil restitution to indirectly use the customer's remaining property as collateral.

You only need to secure a deposit which covers the black-market price of the equipment.

So probably ~30% of face value.