Depends on what you have.
With those short kids-size sofas that they install sometimes as a coach - 60" long - can be a problem to find a cheap replacement.
I have one, and dreading the day I'll need to replace it. Quality is terrible, thin foam and flimsy framework.
Btw, dismantled one of dinette benches and replaced with a decent chair. Needed a space to install a propane heater on the wall. Turned out to be a blessing - the dinette bench was a torture device, difficult to sit or to get in and out. The chair is saving space and is really comfortable. When I removed it, I found that wooden frame was already cracking and falling apart after just one season. Was not worth keeping, threw it to garbage.