How much is your “friend” willing to pay for the use of the equipment usage?
Is your friend capable enough to do the install him/herself?
Has there been a recent increase in power usage?
What things that use electricity does your friend have?
What is the usage that your friend is seeing?
A bundle probably costs around $200. So lets look at what a rental company would charge for something like that.
Here is my local rental company:
GRINDER 7 INCH HEAVY DUTY Rentals Monroe WA, Where to Rent GRINDER 7 INCH HEAVY DUTY in Monroe Washington, Duvall WA, Redmond, Woodinville, Sammamish, Duvall, Bothell, Snohomish, Carnation, Fall City, Snoqualmie WA, and North Bend (gsrrentals.com)
$20/day, $80/week, they don’t list a monthly rate, but it would probably be $160
So, how much would it cost to buy one?
7 in - Grinders - Power Tools - The Home Depot
$130-$200 depending on how good of one you purchase
So, if you need it for more than a week, it is probably cheaper to buy one. At the end of the time you need it, you can resell it. For something that is used, I typically expect to get it for half price or less. But that depends on condition and the item. There is not a big market for used IotaWatts, but I am sure it would be possible to sell one with a sufficient discount. I already have two, but I might be interested in another one (at the right price).