The auto shop experience you had, Photo, comes down to opportunity costs. If they take your job at Keyboard Market prices they can't take a job at Car Shop market prices, which are likely higher. Otherwise he'd be choosing between a keyboard at $50 or a car at $250 for the same amount of time (presumably). He'd choose the car every time. OR he could
offer to take your keyboard, but he needs to get the same money. It's absurd prices for a keyboard, but at least you have the option (I guess?).
I agree it's not a good price, but he doesn't have much choice.
Of course, if he's not busy he'd be an idiot to not take business - though I suspect he has orders coming in just fine.
For the record, I don't think I'm teaching you anything new here and don't mean to be condescending, but it's important to see it from their point of view. Profit (and business) is always good, yes, but why not take the option with more profit?