In reply to:

P.s. I say ahnvelope; thinking it's a regional thing and not a snotty thing.

I feel similarly. I find myself using ON-velope, and N-velope almost equally. As a child, I heard ON-velope more often, but now N-velope is probably more common here in The Shaky Isles, and I probably use it more often than ON-velope, which pronunciation (here at least) long ago lost any connotation of Franglais pretension it may once have had.