Old bulbs cost 20 cents each and last 3-6 months. These new bulbs cost $1.50 each. Do the math and figure out which is cheaper.
You can buy new bulbs for $1-$1.25. Anything more than that you just aren’t looking closely. Old bulbs were about 40 cents last time I was at Walmart. But even using your 20 cents at an average, at an average of 4.5 month per bulb (which would be generous in my house) would break even with a CFL in about 2 1/2 years. Average CFL will last 3-5 in most houses now. That also ignores the fact that you’ll save 75% on energy each and every month. I’ll save about $300-$350 this year on my electric bill due to CFLs (based on my last 4 months of use since I switched 2/3 of my bulbs (none of my CFLs have gone out, I had 4 incandecents die in that time out of my remaining 10).