I have heard mixed reviews on DDM. Like said before some orders have taken 2 months to be delivered which is crap.
If you want a high quality AC digital ballast (non flickering) at a good price and want it in your hands in 3 days order it from my r6 forum site sponsor.
$55 for a single beam kit, $75 for a dual. He will take care of you if you have an issue but with kits in 6 different cars and bikes I have not had an issue yet. One kit is 1.5 years old!
These are not the cheap ebay Xentec, they are the higher end better ballast versions!
I am actually ordering extra bulbs from him right now, because I want to put 5000k in my new retrofit :)