I've got a relatively cheap Redding universal funnel, the little green one. It's always worked fine, but since I started loading a 22 caliber case mouth, it's showed its weakness. It still works, but the seal is sketchy. It does seal on the mouth, but that mouth is pretty narrow, so the funnel doesn't balance securely.
I think it's acrylic. I have some high-end reloading gear, but I just don't think some of these really costly machined billet funnels would add a lot to my practice. I'm betting there's another plastic funnel out there from Hornady, Lyman, or RCBS that will do well for smaller mouths and perhaps another one that will work better for large. Maybe I'll just get the Satern for 22 and use the Redding for the rest.