I have noticed that the 380 Series I GT are pretty cheap, they seem to start at about $25000.

Why so cheap, and what should I look out for?

If its an early build make sure the black strips across the roof aren't warped and there is also an issue with condensation entering early build VRX and GT tail lights. Other than that they are very good. If you find a car you are interested in get the VIN number and go to service and ask them for a report on whats been done to the car. As in recalls and warranty claims. That should be a help in choosing a car.

Good idea, Are the black strips on the top of the car or in the interior?

Good idea, Are the black strips on the top of the car or in the interior?
Across the roof. The ones that separate the roof panel from the sides.

Check the previous owner also .. make sure its not Budget Thrashacar