Standard A type CFL's are easy to find in a pack of 4 for $0.99 (in California)
I don't know if most other states have rebate programs for them.
I usually have the best luck at walmart.
If I cant find the type I need at walmart I go to 1000bulbs.com, they have a huge selection of all kinds.
Like I needed a 25w (equivalent) Decorative Dimable type C candlebra bulb. And they had it! (In other words a very rare bulb.) I was on a mission to replace every last bulb in our house with CFL's.