Pabell, I second what Lynne said I purchased a 5th wheel trailer that the roof was leaking on and was really not fixable, I think I paid like 500 or so and used ALOT of the parts, it paid for itself many times, if you have room and can take it apart it could be an option. Ebay and Amazon can be your friend, reefer vents ect are cheaper on line for name brand items. Craigs list, I have bought numerous things on it, check it everyday the good deals go fast. I also have bought items at my local trailer sales, check and see if they have a clearance area, I bought a door for mine for less than a quarter what full price was. When your replacing items like a vent or a fan look at going upgrade it'll be worth it when your using it, best part is you'll know your unit better than just buying one, and cheaper too.
Terry and Eleanor
94 Softail / 92 FXR
79 32' AMF Skamper 5th Wheel Toy Hauler
97 International 4700 Tot'r