A little late on this, but just thought I’d say we made an LED version of this. You can create it from scratch with the raw parts for $180. Sounds like a lot, but that’s how much a 300w equivalent LED halogen replacement would cost. People claim all sorts of stuff out there, but something over a 300w, 6000 lumen halogen lamp is more than what you can get from typical off the shelf stuff. Guess it’s possible you can get it a lot lower if you just want to set the LED on top of the shade and tie it all together. We can walk you through anything if you’re into the idea. Feel free to post in our forums 
windowled.org