Sleeveless Trench

Just the other day I had an inspiration for a spring time look of a sleeveless trench coat dress, and started looking for one. The only nice one I found was from Burberry but it was about $600 or so. Not sure this is a very long lived trend for me, so don't want to spend that much. However, I found a good DIY suggestion from HonestlyWTF (a truly wonderful blog and resource!). Now I just need to decide whether to sacrifice my Escada trench coat sleeves for this fad...or should I buy a cheap Walmart trench coat to bastardize?