It is almost always cheaper to buy items online. Therefore you can go into a store and try out the items you are thinking of buying (get your size etc.) go home and order them online. Saves a lot of money.
Another must is to search online for promotion codes that will get your items cheaper.
Karmaloop is a great example. Their site had a variety of codes, one of which allowed you to get 15% of your entire order and others allowing free shipping!
(
AGENTSPITS gives you 20% off your first purchase, 10% off ANY future purchases)
Finally if you must buy in store always ask them if this is the best price they can give you. Usually it isn't and they will go lower to make the sale.