I agree with everything said so far on this topic. A $500-$900 would be nice, but I don't see it happening long term, regardless of the "passion" in the Passion Project. Is there any market data on an in-between sized turbo - stock 200hp < ??? < 300hp < .....
Is this just a side project to keep your attention, are you looking to make a few grand and move on or are you scoping out another market segment for the long-term potential? If you are a business, you have to approach with that mentality. You could make the best $500 turbo, but if you make 10 and stop because you have a new passion making turbos for the upcoming 'Brand X car'....well... I would rather buy a from a business that continues production of a product (same model or an improved one) rather than a one-off that may stop production (replacement/warranty concerns).
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Demand refers to how much of a product consumers are willing to purchase, at different price points, during a certain time period. We all have limited resources, and we have to decide what we're willing and able to buy.
While demand explains the consumer side of purchasing decisions, supply relates to the seller's desire to make a profit. A supply schedule shows the amount of product that a supplier is willing and able to offer to the market, at specific price points, during a certain time period. (that is key. Example: you produce, everybody loves them, some of us put off buying the other brand and are about to put in the order and you lost your passion to produce. Or we start saving and while we save, you stop.)
Equilibrium is the point where demand for a product equals the quantity supplied. This means that there's no surplus and no shortage of goods.
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I would suggest some formal market research before you continue down this path. The most successful businesses do. YMMV. Good luck.