I have a Kensington one, it is pretty durable and easy to bend however you need, etc. I think I actually just got it from an Apple Store.
I've been happy with the air vent mount that I got for under $10. I couldn't find the exact one but it's similar to this: http://www.amazon.com/dp/product/B001OMOTAA?tag=priuschatcom-20 like it because not only is it easy to get my phone in and out but the mount itself can be installed and removed easily without damaging anything in the car.
I have one of these and really like it. I use the universal mount. (dedicated iPhone cradle needs to not hav a case.) I haven't mounted it in the v yet but plan to. It has never fallen on me in almost a year. http://www.amazon.com/gp/aw/d/B002K9IPOC/ref=mp_s_a_1?qid=1334892848&sr=8-1 W
http://www.amazon.com/Kensington-Mount-iPhone-Players-Black/dp/B000MPIX3E A number of the Kensington ones have both the vent and window attachments. Both work well, but I feel like the window works better for the v.
Proclipusa.com has specialty mounts for the Prius V. Best I could find. This is the left side mount with an iPhone device holder for phones with a case. The holder is adjustable for different size cases. My case is an iBattz Mojo external battery case and it fits GREAT. Great thing is that it's out of the way, is made to fit exactly for the Prius V, mounts over the AC vent, and while it doesn't block the AC (like a center vent mount would) there is enough AC airflow that the phone remains cool, even with the sun shining down through the windshield. I am VERY satisfied with it!
