Why not buy a sofa second hand through a thrift store or charity shop? Costs tend to be lower and you can always donate it back when you're done with it.
OP didn't specify the sofa was new but this is a great point that I think about a lot. People talk about rescue dogs and make a big deal out of it but then refuse to buy anything secondhand. My "new" car has 190k miles on it and I love it.