Where's best to buy stuff at Staples - in a store or online?

I regulary have to buy office supplies for my boss - a small business owner. About 500 or 700 bucks a month. I don't spend my own money for that but since it's my job to get all this stuff I wonder if I could save some money to make that old grumbling guy appreciate my work. Looks like price you pay in a store is more or less the same as you do purchasing online (though you got to make a $50 purchase to get it delivered to your office for free if you buy online). Is there anyone who can give me some hint about which way is better?