I don't live in your area, so I can't tell you what to expect for cost.
I can tell you that, at least here, upholsterers want to sell you the fabric as well as do the work, and they will give you a better deal on the work if you buy the fabric from them.
In addition, they know about the fabrics they sell, and you can pick their brains about how long-wearing this or that fabric is and how it stands up to children, pets, and snack-eating television watchers.
There used to be women who worked out of their homes doing upholstery, but that's almost nonexistent around here any more.
Check with your neighbors - word of mouth is important in this sort of business. Check online, and see if the upholsterer has good reviews from prior customers. If you know any women who are decorators by profession or hobby, ask them for suggestions.
Whoever you talk to about doing the job, get references!
In many cases, it's actually cheaper to buy a new piece of furniture, because most modern furniture is made to be disposable. However, that doesn't mean you would *always* be ill-advised to have the work done.
We live in an old house with a very narrow staircase, and a store-bought sofa literally would not have gone down it into our family room. I waited for a long time - saving up money as I waited - before I found somebody with an old (probably '60s or '70s), free, full-sized sofa narrow enough to fit down those stairs. It was in good shape except for the fabric, which was dreadful.
The work did cost several hundred dollars, but the upholstery men said that the sofa's "bones" were excellent and that it was definitely worth doing. The result is wonderful to see (I had it done in a good quality, dark red microfiber) and to sit on, and one of our kids has already put dibs on it for when my husband and I are six feet under.