yes, Costco also has an excellent laundry detergent and i also add 1/2 cup of borax for super whites and brightened colors. even if i have a stain i can soak it over night or for a few hours and it will come out.
before costco started carrying these brands and yes, i always took the time to fill out a slip and request them because i knew they would beat out the competitions price. :)
I would get the METHOD brands from Target.
No the Borax isn't from Costco I get it at Walmart or any grocery store.
Borax has many uses so does the arm and hammer washing soda just check the boxes for the uses.