It's not like 100mm is an exotic focal length any way you slice it... Any decent 100mm macro is going to give you the same and much, much more. Say, the Canon 100/2.8L IS Macro is the sharpest lens I've ever used (could even be sharper than the 16-35/4L that I have now), and there are lots of cheaper options in the range like the non-IS Canon 100mm or even an old Tokina 100/2.8. 
While I can understand the appeal of lo-fi and ugliness - heck, I've been dabbling into the area of long exposure semi-abstract looking shots myself - I've done everything with the same tools I'm using for my daily work, without having to buy overhyped (and thus overpriced) old junk. Or the even more ridiculously and gratuitously overpriced modern replica thereof.
While I can understand the appeal of lo-fi and ugliness - heck, I've been dabbling into the area of long exposure semi-abstract looking shots myself - I've done everything with the same tools I'm using for my daily work, without having to buy overhyped (and thus overpriced) old junk.
Or the even more ridiculously and gratuitously overpriced modern replica thereof.