Are you looking for a used set or new? I'd go new and there are a few options:
- DIY. Get the materials from Fabric Warehouse and sew yourself. Get foam off Amazon or another source.
- Measure and make templates for what you need. Look at a place like Coversandall on the net and have covers made with zippers. Get the foam off Amazon, wrap in Dacron and fill the pre made covers.
- Got to a local marine canvas/upholstery shop and have them made.