This topic comes up one way or another quite often. One way to address this is to figure out just the material costs and then factor in overhead: equipment and depreciation, other overhead (advertising if any), labor a reasonable profit margin, etc. Ignoring all of that for now, let’s price out one model – a 26 string fully levered – in two configurations: cheapest possible, and more expense. In the US:
First you need to beg borrow steal or buy a blue print – or design you own. Keeping it simple blue prints will cost about $25 – designing your own about twice that (you will need a drafting table of some sort, paper, etc.)
The harp frame and body will run from $150 to $400 depending on what you do:
All Baltic birch for the frame with Finnish birch for the sound board – $100+ for the body and frame, $50 for the sound board. Total about $150.
Solid wood – let’s say cherry frame, pre-made spruce sound board – $250 for the frame, $150 for the board.
So, OK, $150-$400. How about the rest?
Tuning pegs, bridge pins, eyelets, misc. screws and glue $100. Levers $150 – $420 from least expensive to most. Total – $250 – $520.
Strings: about $150 – $200 depending if some are wound or not.
Adding it all up before stuff like lots of clamps, jigs fixtures etc.:
Total $525-$1125 (did I add that up right? please check my calculator fingers).
Perhaps you can knock off a $100 or so if you happen to have to have some of this just sitting around.
Shall we add in labor, overhead etc? Nah, let’s not I think the point has been made.