If you love data, reams of it, then Terapeak is for you. It can tell you the price on the day in the category, etc. The US market is free (international sites at a price) and online with no software to install.
But the interface is a bit confusing and takes some learning. Even getting to the research page from the home page takes some digging. For the newbie, the mountains of data could be pretty overwhelming, especially without understand what the data means.