Can be found here: http://www.volv.org/zelda/?i=2

It lists all necessary upgrade materials sorted by armor and level, but you can also just check off the ones you have and let the site generate a summary of the total materials you need. This is especially useful IMHO for sets that have repeat items: imagine you just farmed 6x Lynel Guts to upgrade your set of Barbarian Armor to the fourth level and then sold the excess Lynel Parts because you thought you were done with them, only to realize that the Radiant Set you just bought also needs them and you have to farm again … if you know that stuff beforehand, you can easily determine which items are safe to sell.