If you're trying to rent a piece of heavy equipment for a job at your home or business, you may have already found that your commercial insurance or your renters/homeowners policy isn't going to cover the equipment. These policies can offer some liability and medical coverage, but they often do not cover the equipment itself. Using equipment without insurance isn't a good idea, so you need to find coverage somewhere. You usually have two choices: insurance offered through the rental company or through a third-party agency.
If you get the insurance offered through the rental agency, initiating the policy will likely be very easy, similar to how checking a box on the rental form gets you the rental company's coverage when you rent a car. It's one less thing you have to worry about tracking down, and if ease is your thing, going with the rental agency's policy is best.
Another advantage to going with the agency's own policy is that some coverage might already be included in the rental costs. This, obviously, varies from place to place, but it's worth asking about before seeking a third-party policy.
But also like rental car insurance policies, there may be different levels of coverage, and you have to be sure to choose all of them if you go with the rental agency's policy. You don't want to be stuck with having to pay for certain costs because you went with the legal minimum, for example, and didn't choose any extra riders or higher coverage. A third-party policy would likely cover everything in one policy.
A third-party policy, as short as it might be, could be cheaper overall, though this is not guaranteed. Depending on how the policy is paid for (for example, one payment covering a month for a third-party policy versus payment per day -- adding up to a substantial sum -- for rental agency policies), you could spend less by going to another company. This is similar to how a per-day car rental policy can add up to be so much more than one month's worth of your regular car insurance.
Talk to the company you're renting the equipment from. They may have policies that fit what you need and that are affordable, but if they don't, getting the information as soon as you can will give you more time to look for a third-party policy if needed.