We ended up getting this sock monkey costume for $15 from Amazon. It's thick like a fleece blanket, and snaps up like a romper. It doesn't look exactly like a sock monkey, it doesn't have the "butt" details, but it was cheap, and that's what we were going for. I still think it's cute. And I think he'll be comfy. He even left the hat on, which he usually throws off!

Re: PIP DS in halloween costume
I think it's ok that you don't have the butt details, I think it would look weird and National Geographic-y on a human.
DS1 born June 2008 | m/c at 9w March 2011 | DS2 born April 2012
Very cute! I can't wait until next year to dress DS up!
(We're moving Halloween weekend...bummer.)
Bubblegum Explosion
www.facebook.com/TryVermontFirst
I love these two beautiful children!