Download collection feature

It would be nice to give us the ability to download our collection.  Maybe as an excel, word, csv, or pdf file).  

Since this is web-based (no stand-alone app) this would allow us to view our collection while offline (i.e. at work, or inside a store where there is a weak signal, or while you're at a flea market out in the boondocks where there's no signal and you want to make sure you don't already have something they're selling).  

These are just some scenarios where having a list offline is handy.  Heck, I'm old fashioned and might print this sucker out before I go garage-selling just in case my phone dies!

I saw where someone requested for the ability to export the collection, so this may fall into the same category.  If so, please feel free to remove this request.  

Thank you