You'd have to do the math, but similar to boots theory, if you're spending 2-3 times as much for something that lasts 5-10 times as long (50k hours for a good LED vs 1.2k hours for incandescent) you will save a lot more money in the long run (lets assume the 4/$1 deals are a thing of the past with inflation and reduction in production). Also cheap DC converters create more heat than the bulbs with decent ones. It's worth slowly buying expensive bulbs, at least start with the most used lights in your house and replace those with the expensive ones. You can keep cheap bulbs in your closets, spare rooms, etc assuming you don't forget to turn them off often (then you should get the most efficient/long lasting or get one with a motion timer).
I actually swapped out my shower light because it got so hot the insulating wire melted and it created a short. Took forever to figure out, but once I did, I got a nice $30/$40 shower light fixture that went right in the same spot and its much nicer now. I'm just glad the short was running through metal wire/fiberglass and never started a fire.
