Try a simple red tee shirt, with a red canvas tunic over that, then some thick red tights. You should be able to buy a "robin hood hat" like that at a costume store, and the boots, it would be easy to made some leg warmer like things, like a boot cover, if you can match the fabric to boots. This is a very basic, very simple outfit. You should only need basic sewing abilities to make this, and the materials should be cheap to get.
i've been doing superhero costumes for a while, i'd suggest getting red underarmor shirt nad pants, boots pick up the flip over buccaneer/ pirate boots adn nu-life meltonian spray in gold, this is an awesome flexing spray paint i used these on my damian wayne robin green doc martin boots, next get the chest emblem out of a fabric that wont fray i tend to use faux leather/ vinyl it adds an edge and looks different from everyone else "spandex" costumes. the hat an be made easy, go onto the superhero costuming forums adn look up cyclone from dc comic she has a green hat like that one, they have a tutorial on how to build a real easy one. hope this helps, let me know if you need help and i'll point you in right direction, good luck.