Are you handy?

I've installed fan vents, soooo easy. Just drill a hole for your SawzAll, cut the hole and drop it in, caulk and go.
The new, super-light, turbine (or rotary) vents are AWESOME for problem areas! They don't rust and don't need a lot of wind to work, the new bearing systems are slick.
I used to put them in in five min. and they save serious ducats.

[glatt]

Originally Posted by rkzenrage

I've installed fan vents, soooo easy. Just drill a hole for your SawzAll, cut the hole and drop it in, caulk and go.

I know you have done this and I haven't, but I would never trust caulk alone to keep a hole in my roof water tight. Flashing is needed.

Edit: Flashing around a fan, depending on the shape of the fan, will be much like flashing around a skylight.