During Christmas, eBay did a thing where they had a new deal every few hours with a large percentage off. It must have gone over well b/c they have continued it. I have seen items up to 90% off (and as low as 10% off). They are usually through buy.com's eBay account so they are from a reputable retailer. They also always have free shipping. Here's the link if you're interested: http://pages.ebay.com/deals/ They change daily
If you look at the top left next to categories, stores and motors there is a green tab that says deals. You can also click that.