Male Bovine Feces! Yes, initial cost is high, but coming down rapidly. With a little creative shopping, I paid around or less for most of the 300+ LED bulbs in my house than halogens would cost… and that was 2-3 years ago. There were some bulbs I paid a lot for (like $30-$35 each)… the PAR20/95 CRI/550 lumen, the PAR16 500 lumen, and the MR16 490 lumen ones.
Construction quality far exceeds that of CFL’s. Output exceeds what any of my halogens put out. Failure rate has been exceedingly low… like three bulbs have died… all of them driver failures. Before, I was replacing at least one halogen bulb a week. Between electricity and bulbs (and not counting the time saved not replacing hotwire bulbs) I am saving around $100/month with LEDs. Total payback time was around 3 years (could have been a lot less, without some of the experimenting and splurging on those $30+ bulbs). I need to sell of some of the earlier bulbs that I bought and replaced with more advanced ones.