Most of the big box stores carry it

I've seen the insulated stuff at our Lowes store too. Was expecting a huge
roll, and was surprised to see it in such a small box...

Plain PVC pipe won't prevent the condensation, but does tend to drain
better.

My "attic" is actually within our heated space, sort of an oversized
soffet. So, I didn't have the condensation issue to worry about. But, I
still installed the PVC with a slope towards the wall vent. Any moisture
that collects inside the pipe will drain off to the wall vent, and not back
into the ceiling fan.

If my attic were exposed to cold air, I would wrap the pipe with
insulation, or just bury it under the normal roof insulation if possible.

Anthony