Ttc website has a price check feature you can use. This is especially good for those on console. There's also fox box for discord that does this for you.
Unless you can use a mod like Master Merchant, the best way to determine mat prices is to go shopping for the ones you want to sell. They are commodities and usually sell in tight price range and are fairly consistent over time. So, find the prices other people list at to get an idea.
Enjoy the game, life is what you really want to be worried about.
PakKat "Everything was going well, until I died"
Gary Gravestink "I am glad you died, I needed the help"