It's 520KHz, not 1MHz. There isn't really anything special about the parts... they are off the shelf and anyone can buy them. The biggest trick would be to get enough copper in the high current loops and a compact layout to minimize Cu losses. The "home builder" could make one of these pretty easily... however, you are correct in that they won't be able attain an efficiency quite that high, but I wouldn't put the low to mid 80's out of reach.