Replace the random markup on only some unidentified items sold by a shop with a multiplier that is always between 1.0 and 2.0, but is always the same within the same shop, and is applied to all unidentified items in it. The multiplier is biased towards the lower end of that range by taking the square root of a random number from 1 to 4 (or mathematically equivalent constructions that minimize reliance on floating point calculations in the code, such as taking the square root of a number from 25 to 100 then dividing the result by 5).