spy from team fortress 2

I look at things I can buy with ref and compare sell and buy prices on scrap.tf to backpack.tf and it usually does not work but there are times I find a item that's sold for a lot on backpack.tf and it cost way less on scrap.tf and most of the times its the other way around i sell on scrap.tf and buy on backpack.tf

Hi I am trying to find out prices of items I want to sell and searching it up on google does not always work, so is there a way I can find out the sell price with out the item in my inventory?