I've finally buckled down and made a fully fledged pattern! You can either purchase a paper copy ($25, including shipping via U.S. Mail) or a digital copy formatted for 8.5x11 printing ($18) at my website:
http://barefootsewing.com/doctorhorriblepattern.html Each version of the pattern is suitable for adult sizes XS-XL (waist sizes 27"-41"), and both contain six pages of illustrated instructions and fabric cutting guides.
I am also still taking orders for lab coats if you're not interested in the DIY route. Red and white coats cost $120 each plus $10 shipping.
Thank you all so much for your support when I first posted this pattern here two years ago. I couldn't have done this without everyone's help! :)