A high margin would be 40-45% (66-80% markup), low end would be around 20% margin (25% markup) in my experience (as an employee). so for a $500 bike a 40% margin is $200, $300 original cost to the shop. In markup terms, a $500 bike that costs $300 wholesale is 200/300 = 66% markup. Keep in mind this is not profit.