I was kind of happy Gareth decided to be Edd - 1) I like Edd as a character, he's a little genius science nerd, although if he's not careful his OCD is going to get out of control, 2) Gareth is a lot like Edd, just as sensitive but more outgoing, and 3) for a costume, it'll be a cinch, red t-shirt, red knee socks, a pair of blue or black sneakers (I was thinking Converse All-Stars - do they have those in kids sizes?), a black stocking cap and I have a pair of stretchy purple bike shorts that I think will serve for Edd's baggy shorts. So simple. Compared to Angus, who wants to be a pharoah. That's going to take some work - especially on the cheap.
However. I've been perusing various internet sales places and do you think I can find a plain black stocking cap anywhere? They're all either too short or too long, and all of them have some kind of freaking logo embroidered on them, or a stripe in the wrong place. I have yet to check out some local sporting goods stores, though; if necessary, I'll turn it inside out and attempt to sew a pair of stripes on the sides, and maybe add some yarn for his hair in the back.
(Everything you didn't want to know about Double D)
*And btw, I can't stand the illustrations Wikipedia has of them - it looks like early concept art and they aren't quite so apelike now. Edd, especially, no longer has the underslung jaw shown there.