Making a Property Offer

[Rob Bianco]

I've been reading some books from Bigger Pockets and a recurring theme seems to be to get a deal on the sale price of the property you're interested in. To me this sounds like you should offer below asking price. My question then is how low is too low? 

There are a few properties I'm interested in, but I've considered offering 20% less than asking price, based on something I read, but that sounds pretty low. On a $500k property we're talking about $100k .. I can't imagine any seller going for it.