Ready made replacement cushions for rattan sofas?

Does anybody know where I can get ready-made replacement cushions for a rattan sofa, love seat and chair? They're pretty standard in size--I looked at the sets in K-Mart and measured the cushions that came with them--they would fit mine. K-mart only seemed to have high back chair cushions for sale a la carte, though. While I could probably use three of those across on the sofa, two on the love seat and one in the chair, they are not very plush to sit on. I don't want to wait for custom made cushions, but if I've gotta I've gotta...

Any tips appreciated,

Islandlola