Not that expensive I would argue. Bicycle tubes do cost more than regular steel but they also keep me busier for longer 
It’s all the other gubbins on the bike that add up to a lot. That’s why a couple of my builds that were for me have been “frame replacements”.
We had a great discussion here about it all 
going into “animal laborans” vs “homo faber”.
There kind of is a trade-off between having fun and giving the customer the best value for money. I think so anyway, but there were some interesting and learned points made on both sides.