I did a quick cover of all of my cushions with indoor/outdoor fabric from Joann's. I had a coupon and it was a good price overall. I think maybe around $100 or so for all the fabric I needed. Mine wasn't perfectly covered as I just did more of a "fitted sheet" so I could slip them off and wash them if desired or if someone wanted to go back to the yucky brown ones when I sell the trailer. You can see them in my non FB trailer updates folder
good luck and can't wait to see the updates!