I don't believe there is a tool, but if you wanted to put in the effort you could check the ending dates of the "sold" listings and compare their prices.
One thing to keep in mind is that retailers normally place items on sale entering the season to which the items apply and then discount them again afterwards.
For example, a grocery store will run ads like crazy for "healthy" meals right after the 1st of the year to coincide with new years resolutions. They will do the same with cleaning supplies as spring arrives. My point? The beginning of a season is when there is most demand for the types of items it pertains to. It is also the time of most competition. For example's sake, if you are trying to sell, say, all-purpose cleaner. The normal retail price is $5 and you are selling yours for $4 to try and maximize your dollar. Well, at the beginning of the season, it is likely the target demographic will be purchasing cleaning supplies and these items will be run on sale. Now the regular priced $5 supplies are $4 or even lower. So why buy your "new" product when they can grab one brand new for the same price or less? Sure, there will be those who don't put two and two together and still buy your product for as much/more than the discounted rate now offered for the same item new.
So in short, when demand is highest, so is supply.