Cree PAR38 LED spotlight.

[ALToronto]

David, your most recent choice is a good deal - almost on par with Aliexpress pricing. It's still a little better if you buy direct; you can usually get them for $9-10. The light bulbs in your first post, however, are considerably marked up by HD - online, they're about $3-4 each.

So far, my experience buying directly from the manufacturers has been very good. You do need to shop around, though - the prices can vary dramatically.

Everybody seems to be using either Cree or Epistar/Bridgelux. Are they of comparable quality, or is Cree noticeably better? I've also been searching by lumen efficiency - 80 lm/watt seems to be standard, but you can find up to 135 lm/watt. Is there any validity to these ratings, or is it an unreliable measure, as David says?