Got the window from ebay, it was around 80$. The only other thing i had to buy was the sealant tape(forgot what its called), putty tape? Otherwise it was pretty easy. My advice, measure 5 times
have a shoot and just do it. Cover everything in the trailer, or tape it off. There will be a lot of stuff flying from the walls and insulation being cut.
Only thing i regret is not getting a bigger one!!!
still thinking about it though.