I've seen a couple of tutorials for making roman shades out of inexpensive mini blinds. Here are a couple I found just by googling, but there are a lot out there. Take some time to explore on pinterest and google.
http://involvingcolor.com/involvinghome/no-sew-roman-shade-from-mini-blinds/
http://littlegreennotebook.blogspot.com/2013/02/diy-roman-shades-from-mini-blinds.html
If you do this, please come back and post how it went -- I've been curious to try!