Whatever you're charging for these things, it's just right, and if anyone thinks it's too much , I suggest that they make a scaled drawing and take it to a local machine shop and find out what they would charge to make one( 10 years ago the only local shop that took on single jobs charged $100 a hole for each hole that had to be punched in an item , I can't remember the prices for bends and shape cuts... and that was with my cousin working there). Paying for qualified machinists is not cheap and they take into account wear on tools and supplies on every job( if they didn't they'd go bankrupt).
For people who don't do any kind of regular fabrication, they would be shocked to find out what a piece of steel plate that size costs these days , BEFORE you start doing anything to it
Then of course, before any profit, there's consumables on the plasma rig, insane amounts of electricity consumed as the KWH wheel spins in high gear while the cutter and compressor go full tilt ( all of which makes for a beautiful set of cuts )