Buying holiday gifts or any other purchases online will definitely save you time but often with shipping costs, you'll end up spending a more in order to save the hours it would take you to go to the mall.
The good news is that you can almost always eliminate those additional costs by just searching online for a store promo code. Just go to Google and type in "[store name] promo code" and presto! You will typically get a series of different discount and free shipping codes to choose from. Sites like RetailMeNot.com will tell you the success rate of these codes. If the rate is 80% or higher I've typically had luck using the codes.
You'll not only save money and time but you'll feel good knowing that you didn't spend any more than you had to. Shopping is much more fun without buyer's remorse!