Those things (dehumidifiers) are fantastic, and will suck the water out of a concrete floor. If you don't run an air conditioner in your shop these things are a necessity to keep your tools from rusting up. I still use mine and sold about 30 at last years Rally.
They only run in summer time, or when temperatures are at 55 degrees or more inside the shop, but you don't usually need to dehumidify in the winter anyway. I highly recommend them. And if she has the buckets, that's a big plus. I fill mine up with water every 24 hours. It's crazy how much water gets in the air in the garage.
A friend of mine was selling these on craigslist for $45, so you can buy at that price and resell and double your money. Fantastic price. Thanks Mahala! Good offering.