Profit/Expenses

Hey guys, so I'm trying to figure out the best way to set this up. So I'm setting up an Excel document for a cell phone repair shop. I need to figure out revenue at certain sales numbers, payroll cost, profit, and profit margins. I have all four of those already figured out. But now I want to add in the price of one repair cost at different expenses. For example, lets say I have an iPhone 7 and 7 plus. If it costs me $10 for the iPhone 7 and $12 for the screens, I want to figure out how much I should charge the repair to achieve certain profit margins. Is there an easy way to set that up?

So the AVG profit is an estimate of the average profit I make per phone sale. So sale of phone repair - cost of phone part. I want to hone down by putting specific values for the cost of the phone part. I want to do that for every repair and then calculate from that data, which phone repairs I should push for the most. Also run simulations with dummy data on estimated sales. I can do it manually but I'm sure y'all know a way more efficient way of creatinng the data. It needs to be simple enough that if someone else looks at my data, they can kinda decipher what it means.