Doesn't help.
Unless you know the street price of something, (i.e. the typical selling price after haggling or the standard one for suppliers wanting to trade on a high volume, low margin basis) then there is nothing to compare against.
For example, one type of supplier may have a high level of service and need high margin to cover it. Another may simply be selling at lowest price. A third may set a high list price, deliver nothing special and rely on most customers paying the asking price or something close to it.