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.