Upholstery shops may sew slipcovers, but it's unlikely. You will need to find someone locally. You can ask for references at fabric stores, local newspapers or by word of mouth. All sofas are different so the slipcover maker would need to come to your home, pin-fit the cover, take the cover to their shop and sew it. They would be able to tell you about required yardage and appropriate choices of fabric. Slipcovers are simply covers-- no need to remove your existing fabric. Prewash all fabric if you plan to toss the slipcovers in the washing machine. Hope this helps.

Finding someone to sew slipcovers has proved pretty difficult in my area, so I totally understand the challenge you face. My options were to go with a full service interior decorating company that offered upholstery/slipcover/drapery making or find a home-based or small business individual. Unfortunately none of the individual home decor sewing people advertise around here (I check Craigslist, classifieds, etc.). In my area word of mouth is the only way to find someone who makes slipcovers. I couldn't even get references from fabric shops. Hopefully it will be easier for you.

So I got what I felt was a ballpark price by using the calculators on a couple different on-line slipcover sites as well as pricing Pottery Barn sectional slipcovers.

What I found was that to have a sectional slipcover made in a fabric heavy enough to hide a dark fabric underneath would have cost close to $2K.

However, to replace a high quality sectional probably costs at least $5K, so the slipcover cost can be justifiable. In my case, it wasn't.

I've attached a link to a site that explains differences in slipcover fabrics, as well a link to slipcover workrooms around the country.

Finally, I don't think I'd be comfortable ordering a sectional slipcover on-line. I'd want someone to come out and pin fit it. Good luck!

Here is a link that might be useful: Slipcover fabrics

If you can sew, making slip covers yourself is kind of fun.

You can always try making a pillow cover and see what you think.

Custom is your best best bet. You will get the best fit and therefore, the best look. I was lucky to find a local person who does slipcovers to do some furniture in our sunroom. That was several years ago and they are wearing great. Our fabric? Dropcloths. I washed and bleached them to the desired color. The fabric turns out very soft with a nice weave and wears great! There are many fabrics you can use and there are plenty that will be thick enough to cover the original covering.

Heya, have a look at this page:
http://comfort-works.com/en/custom-sofa-cover-loose-couch-slipcover-17

As a ballpark, custom 3 seater slipcover with us is roughly $495 with fabrics, and the customisations included in the price (skirt, pleats, piping etc). Remember to get some samples sent to you before pulling the trigger. Hope that helps! Henry