And where can you buy those?
You'd have to keep an eye on the "Mac's Customs" forum here:
http://www.candlepowerforums.com/vb/forumdisplay.php?f=96
He occasionally builds them in small quantities and sells them.
You can also find them in the Customs and Mod B/S/T forum here:
http://www.candlepowerforums.com/vb/forumdisplay.php?f=96
The most substantial benefit of purchasing a Mac custom vs. the Mircrofire is the reliability of the parts and electronics. He uses the best bulb and ballast available anywhere in the world. Usually a FiveMega, high quality, custom battery holder is used. They have machined aluminum reflectors and UCL lenses and it's all housed in the rugged and proven maglite body. Other custom features are also offered such as finning, body machining and a tail switch.
Besides the extreme quality of the product, it's nice to know that your light was built with pride by someone right here in the CPF community. If you ever have an issue with your light, which would be very unusual, you know without a doubt that you'll be taken care of.....DX warranties on the other hand can be hit or miss.
I just thought I'd mention it because the price difference is so small and the quality difference is so great...at least in my opinion.