Professional layouts will average $375 per sq ft. all inclusive. Pure cubic time. No one is getting wealthy at that number. Paid but not wealthy. You will find that different subs will do buildings, mountains, electrical, track work scenery. No one person is great in all aspects.
I have worked over D.I.Y bench work, but only with time and material billing. No package pricing on existing problems. Trust me, in the few dozen jobs where the wood work was already done or partly so it was problematic and required considerable rework. Warped pine plywood, many small jig saw scrap pieces used, NAILS!! High fine thread screws that can not be screwed down, open knot holes, 1/4" plywood, difficult to crawl under, severely unlevel platform with no leg adjusters, no consideration for curved track on inside openings, access pop ups which would not work with the track plan, just an unending supply of surprise problems.
IMO, rethink that. Bench work prices only run about $40 per sq ft. About 10% of the overall job.
