Home D has this bitching 4" one:
http://www.homedepot.com/buy/building-materials-heating-venting-cooling-hvac-parts-accessories/master-flow-4-in-goose-neck-vent-in-aluminum-132939.html
It appears that MasterFlow is really a company named GAF? They make this one (It is part number GNV4A) which I found elsewhere on the GAF web site. But this site is for all of the other "goose neck roof vents". A regular goose neck range vent looks inappropriate for a residential roof though.
http://www.gaf.com/Roofing/Residential/Products/Roof-Vents/MasterFlow-Chimney-Roof-Caps-Accessories/MasterFlow-Chimney-Roof-Caps-Accessories.aspx
Also, HomeD will sell a GNV6 if I really wanted one:
http://www.homedepot.com/buy/building-materials-heating-venting-cooling-hvac-parts-accessories/master-flow-6-in-goose-neck-vent-164902.html
Somehow, I blundered into the model I want, except offered by Lowes' and it's from BROAN:
http://www.lowes.com/pd_327605-14-634M_0__?catalogId=10051&productId=3148537&UserSearch=634m&Ntt=634m&N=0&langId=-1&storeId=10151&rpp=24
Lowes has a crappy delivery time, but look, it's at Amazon too:
http://www.amazon.com/Broan-NuTone-634M-Roof-Cap-Black/dp/B0013G31B0
