You will find as many answers as you find folks who have done it, and they will be all over the map. We just started this process a few months ago. In the last year I have spoken to shops about everything from full body paint, to flooring and upholstery. In some cases bids vary by up to 3X. When it comes to major wall repairs, I would talk to Precision Paint and Mike's Custom Painting, both in Bremen In. They both have a reputation for doing quality work, and have done extensive work to Alfa brand motorhomes, which frequently require full wall replacement prior to repainting. When it comes to other work, sometimes creative solutions can save a ton. Tomorrow I'm working with a local kitchen installer to make replacement countertops and a dinette table for our rig. I'm removing the old tops to use as patterns. He will fabricate new Formica tops, working onsite, and I will reinstall them with new sinks and faucets. Replacing everything will run me about $8-900.
By the time it's done, we will have a 34' nine year old rig with new full body paint, new LED lighting inside and out, a new ultra-leather recliner, and matching reupholstered dinette and sofa, new countertops, sinks and faucets, new toilet, and new flooring throughout, for roughly $17-18K. I could of went with the highest bids on all this work, passed on doing a lot of it myself, and easily spent $45-50K, which would of been a very poor decision. It's a Winnebago that fits out needs and has served us well, so I don't hesitate to upgrade it. Good luck with whatever you decide.