My LHBS has 3 # DME for $16. Definitely more pricey than online. Yeast is also much more expensive at my LHBS (hence I'm freezing aliquots of my staters for future brews).
If I have time and plan ahead, I'll buy ingredients online. Otherwise, pay a little more at the brew shop. The good thing there is you have helpful, experienced people to talk to in the flesh. There's something to be said for that.
"Brew like a monk, Drink like a fratboy"