Me and my husband went as Teenage Mutant Ninja Turtles for Halloween last year. How did we do it:
I used a cloth painters suit you can buy from home depot. Paint them green with spray paint. Buy linen cloth based on the color you want to have purple, red, orange, or blue and cut them in strips to go around your elbows and knees, the length depends on the size of those wearing the costume. Sew the end to prevent fraying, or you can also use material glue.
We bought the masks for little to nothing. As Michaelangelo I ended up making my own nunchucks. I did this by taking medium sized paint rollers wrapping them with brown packing tape, and white packing for just the ends. I linked them together with a skull and chain necklace I found, and removed the skulls and simply attached them with more white tape at the ends. They were actually very sturdy and I was very impressed with them.
For the belt buy a little brown linen cloth to go around the belly, and the gray Logo at the front is simply carboard painted gray with the letter R, L, M, D in black pen and then taped on the back to the brown linen.
The Shell was made with a light brown leather seat cover you can buy from Walmart I cut it in half. The larger half was filled with sheets and then sewed back up and spray painted green, the smaller one was placed on the front as was held in place by the belt. You can buy green gloves for the hands, but I took surgeon gloves, and painted them green.
And that was all, very simple, and very fun to make.