Most places have 2 costs....one if you buy the fabric from them and another if you bring the fabric.
For a simple one cushion sofa without tufting my guy charges $500 labor.

A local upholstering business here run by a mother and daughter charges $20 an hour.

I find it hard to believe someone could upholster it for $285. I know price can vary depending on locale but that is really low. In my area, a chair (such as a wingback or recliner) starts at $450.
Make sure the estimates are apples to apples. IOW's, make sure each upholsterer is including possible replacement of stuffing and/or foam, new welting, tufting, or anything extra you're wanting.

I think I paid $600 plus fabric about 10-12 years ago. It ran as much as a new sofa, but I had ordered the sofa custom and still loved it.

About 7-8 years ago I looked into having a couch recovered. I'd paid about $1,200 for the couch about 10-15 years before that. Calico Corners was going to charge $1,200 plus cost of fabric. I bought a new couch.

I know Calico Corners is probably not cost effective and I might have gotten better quotes elsewhere, but that $285 quote does not sound right to me. I would be very suspicious of that one.

I recently paid $485 (plus cost of fabric) to reupholster a chair that did not need any new stuffing/work done.
Another chair that needed the cushion reworked was $650 (again, without the fabric). These were standard sized chairs with no tufting. I can't imagine anyone doing a couch of any size for under $800 here in the Chicagoland area.

I just got a quote for a couch that included some cushion rework. Without fabric, $950. I decided not to do the couch so I didn't get other quotes, but when I got quotes for another project this guy was on the cheap side.

I had a recliner upholstered recently and it was about $500 plus fabric.

I paid $825 plus fabric to have our kidney shaped sofa reupholstered last spring. Calico Cornered wanted over $1100 during a 20% off sale.

Around here it's $1200 not including fabric--- and that isn't for a large sofa, either. Your estimates vary a lot.....buyer beware...