My kids last year went as Steve, Blue and Magenta (from Blues Clues).
My son had a Steve Shirt we found on a garage sale for $1.00 and he wore
khaki pants and brown oxfords. My girls had sweatpants outfits so I
sewed on blue spots and pink spots. Then I sewed a little hood with a
drawstring and made ears from felt and cardboard and attached them.
We had most of the stuff, but I probably spent under $10.00 for
everyone, as we had most of the basic clothing.