As you likely know Borders Books is going out of business. I don't know if this sale is going on Nationwide but My local Borders had stuff at 80% off, nothing over $3.
Most of the stuff was pretty picked over on Sunday, and there were long lines at the checkout.
One thing you may want to look into is a Trading card price guide. regardless what you think about the prices in them, I believe they remain a useful tool for looking up cards and sets. At $3 they are a much better deal then the typical $30ish. The only one that the local Borders had was the SCD 2010 guide which had cards from 1981 forward.
Beyond that they did have a fair amount of sports books - not a ton of baseball, but lots of football. CDs and Movies are also on sale, but you would have to dig pretty deep to find something you like. Magazines are almost a decent deal at 90% off - If you have never picked up a Baseball America and your a fan, this would be a cheap way to introduce yourself to the magazine.
They were also selling bookshelves and other similar items. Those were priced according to size maybe $25 and up.
Locally the Sale ends Tuesday,