I get mine at Home Depot, where you can get a six-pack for about 13 dollars. I replaced about 40 bulbs in my new house and it does make a difference in the electric bill. The fourteen lights in my kitchen and family room use 196 watts. Before, they used over 900 watts. Just those lights save me about 100 dollars a year. Well worth the initial up-front cost.
I use all the savings from the bulbs to pay for my christmas light display, which burns about 90,000 watts an hour.
But I did switch to "Energy Saving" christmas lights, which use 0.2 amps per 100 lights instead of 0.34 amps per 100 lights.