I've been using DDM Kits for over 12 years with great success. I've only had 1 failure and they fully warrantied it.
I've used their normal $29.99 kits the most with no issues. Some vehicles i've put them in do require a relay harness. These kits are just a normal HID kit and do not have any power capacitors or power reserve for canbus equipped vehicles.
I've used their $119 ULTRA Canbus kits for the past 2 years with great success also. I haven't had the need to use a relay harness with these kits. They've worked great with no issues at all. Full plug-n-play. This kit has been in my explorer since last May.
They do offer other kits that are in-between those 2 I listed above. I have no experience with those kits. Judging by my experience with the kits I listed above, I wouldn't hesitate to try them out.
If you plan on using them on anything with an Auto Lights on feature, I would suggest getting a canbus kit in order to avoid any issues with a no light start-up.