well, i can tell you who NOT to get your centers from, and i'm sure that Jeff can back me up, as he was the one that had to take about XXXX machine hours to get them even usuable... (i say XXXX cuz i don't even know how long it took, but forever i think.)
Copperhead Fab seemed really cheap, until i got the first set of centers, and at that point, i realized they were VERY cheap, not made the best. The accuracy of the cuts were insanely awful, and the lug holes were just blown out with a plasma. The gap between the hub and the hub hole in the center had more gap than is even acceptable, and when finishing the lug holes, would leave an unacceptable amount of material next to the lugs.
Here are some shots of the first centers he cut for me.
So, due to the awful plasma cutting and ill measured pattern, i demanded he cut me a new set. I contacted Jeff to see if he could do machine work on the new set when they arrive. I requested that he cut minimal holes where the lugs go so that jeff could machine them how they should be, and to cut the center for the hub at right below the diameter of my hubs so that jeff could machine them.
They came, and the cuts all sucked again, but jeff made them pretty.
so, what i'm saying is, dont get them from copperhead. Stazworks had nice pressed centers, as does usa6x6. If you want flat, make them yourself, or have them made locally. if you know someone with a waterjet, it should be a no brainer.