I always make my own.
But if the have the cheap stuff on sale and the box stuff is cheaper than just plain noodles. I buy tons and throw the cheap fake powder stuff away, cook the noodles, add cheese, milk and butter and I am good to go.
Just the other day, I found Kraft mac & cheese (the kind with the powder) on sale for 50 cents a box. I bought 10 boxes. I threw all of the powder out (I did save one for dh's popcorn), and put the mac in a glass container with a lid.
This will be great for mac & cheese, pasta salad, tomatoes and pasta and anything else I need pasta for.