I don't bother making beef or chicken stock, too much faffing about roasting and stripping bones, plus you need a great big pot to make it worthwhile. On the other hand a quick veg stock is so easy I always do it if i'm going to be making risotto (another dish that is very simple but people think it's hard to do).
Italian sauces I always make from scratch simply because I can. Indian sauces are a different matter! I've given up and now use a jar with extra fresh tomatoes and coriander, and it's not half bad.
I make a lot of soups from scratch, again because it's so easy, but also because I know exactly what's in it.