We have a club member that does not fly but assembles ARF's, builds kits and scratch builds. He was a master craftsman by trade before he retired.

He will build/assemble anything you want and to any level you want. I recently saw a GP Super Stearman Arf that he just completed. When I spoke to him about it it took him roughly 100 hours to complete the assembly, BUT you could not find the seams where the wings joined, where the tail feathers where glued on. Also those little rivets that come with the plane were hand painted on, the 2 pilots that come with it were completely customized to look the part, he took the fake engine and where he cut it out for air cooling he applied a thin screen and painted it to match the rest of the fake engine so at first glance you could not tell it was a screen. He checked and adjusted all wing and tail incidences and a small host of other little tidbits not to mention he redesigned how the top wing mounted which made it a ton easier to do and virtually guaranteed no changes in the top wing incidence during field assembly/dsassembly

He charged the owner $1500 for the assembly and the owner had me do the maiden. It needed absolutely no trim, balance was dead on and it flew very well. This plane could have easily been in a museum as it was as scale looking as could be and probably one of the best assembly jobs I have ever seen.

He did a scratch built (not kit) 90 inch TaylorCraft for another person that I got to look at up close and personal. Total cost for only the build (labor) was $3500. The quality was right up with the Stearman. I hear that plane has won many first place trophies

Yes he is expensive, but he is what one would call a master builder. He is good and people around here know it. I asked him to do my Stearman for me and he said he would not be able to get to it for at least a year, he has that much to do. I am told by other members that every plane, no matter what it is gets all of his attention until it is done his way. Every plane needs little to no trim. If I would not be so impaitent, I'd buy a Carden and turn him loose on it because I know what I'd get would be top quality at what I would consider to be a very fair price.

So it all boils down for me is I'd gladly pay for quality work. I do know that ARF's are a hit and miss thing and would expect to have to pay for someone to go over the ARF inch by inch and adjust as needed.

As has already been said you could do "levels" and we are going to assume that you do decent quality work.

Build strictly by the manual (cost of the ARF)
By the manual with strengthening in obvious areas (Cost plus $50)
By the manual but not the whole ARF is gone over and corrected aa needed (Cost plus $200)
By the maunal with all of the above but now you start to pull back covering, fill and sand seams at to hide them. (Cost plus $400)
All of the above but now wing/stab incidences are gone over and adjusted as needed (Cost plus $600)

Well, you get the idea

I know the numbers are somewhat high as you get into the nitty gritty stuff but it should be as it will take allot more work and thought to get it right. Labor is not everything, you time and having to think through a problem is also valuable. Ask any one who is a consultant