I just went through all this a few months ago so I'll relay what I know.
Option1:
You can get a custom cover made from many different suppliers at a cost of $200 and up (sometimes way up) depending on materials used. Type "custom car cover" in google and you'll get a bunch of vendors with search engines that allow you to input vehicle model, etc.... These covers are generally well built with mirror pockets and stuff like that. I would consider this if I owned some kind of exotic car, but I don't.
Option2:
I didn't want to pay that much but I wanted good breathable material that prevents condensation ,doesn't scratch paint, repels water, resists tree sap, and doesn't heat up on hot days.
I found a manufacturer called Budge that makes generic covers for full size SUVs like full size broncos ,ram chargers, and blazer/jimmys. The size is (17'L x 72"W x 64"H) They have 3 types:
UB-2 - Budge Lite SUV Cover (Cheapest around $50)
UK-2 - The Premier SUV Cover (More expensive around $75)
USD-2 - The Shield SUV Cover (Most Expensive around $90)
I ended up buying the USD-2 since my truck has new paint and will be parked outside in the rain under a sappy tree that has already completely ruined the paint on another truck. It appears to fit fine on my 72, but is a pain trying to put on and take off a 10" lifted rig with 35s. Especially in the wind. I also bought their cable lock CBL-1, but that was a complete POS and I wouldn't recommend it.
Cheapest price I found (incl shipping) was
www.bestpriceautoaccessories.com
Also, if you have nice paint and you want to keep it that way, you need to wash your truck before putting the cover on or you'll grind any dirt/dust into the finish.
hope this helps,
ottoman