Maybe I can help. I do a lot of this.

Just about any ARF is worth $150 bucks plus parts to assemble, detail (tighten and seal covering, add glue where needed, beef up things like landing gear and wing mounts, fuel proof, graphics if any, etc), install landing gear (more for retracts) radio gear, fuel system, and engine, cut in cowl and install, along with all the control devises. This would be for up to a 90 size. You already know about how long it takes to do all this.

I charge more for larger planes. Also, Any mods or extras like cockpit detail are extra.

From $150 up to $300 and even more for giants, for just ARFs, depending on the size and type. I don't cut corners, I use the correct glue in all the correct places, and I am neat and clean about it. They always look as good as they can, I'm told.

Kits are another story.