As samc said, it mostly depends on how good (or poor) the crush is at your LHBS. With my grains crushed by the store I usually got 60% efficiency. First batch with the Barley Crusher it jumped to around 75% and I'm within 1 or 2 percent of that every time. I'm happy with 75%, but I'm still tempted to crank it down a bit and go for 80 or 85%.
It's also so much more convenient and cheaper for me to buy in bulk. I can do less planning ahead and brew anytime I get the urge, since I always have enough for several different styles.
Bottom line - pull the trigger, you won't regret it.