The $100 represents a nominal fee/bid to buy the house at foreclosure auction. They're saying that bidding starts at $100 ABOVE what's owed on the home to the bank.
If you haven't bought a home at foreclosure auction, I wouldn't suggest it for many reasons. Stick with something that's listed and conveyable, otherwise it's a minefield for someone new at buying this way.
There are tons of properties on the market at similar prices in similar neighborhoods. Let me know if I can help you with a list or showings.
Scott Miller, RealtorÂ®