I picked up a borla rolled angled tip for super-cheap on a lucky auction on eBay. I cut the split part (for clamps, it is split but doesn't have a clamp built on) off, scuffed a bit with sand paper, and painted it with several coats of high heat black and it has held up for almost 3 years now with no chipping, rusting, or excessive fading.
I was unable to find any rolled and angled tips that were black but my local exhaust shop had a few that were just angled or rolled (not both) and already black.
Maybe ask at a local shop? Mine had a catalog with several pages of just tips.