I buy almost anything I get from Mancini at shows. I've had issues in the past, but it was so long ago, I don't remember what they were. I just told myself I would use them sparingly, and I have.
I ordered a billet rear main seal retainer this past winter, and it came without incident. I don't like not having a shipping quote on stuff, either. I try to avoid ordering from them just because it's a headache. If someone else makes a billet retainer, I will likely use them in the future.