Doing this on a phone which is a little daunting, but we shall press on valiantly regardless.

1 of 1 forever, unless one miraculously appears out of a private backpack. Stranger things have happened. I paid 60 keys pure for the Chemistry Set. I'd rather like to price the completed item but alas, no can do. I'll do this instead.

Backpack of buyer before: http://backpack.tf/profiles/76561198067161406?time=1439449200

Backpack of buyer after: http://backpack.tf/profiles/76561198067161406?time=1439535600

This should work. The set hasn't moved in months, and it's quite happy to sit in my backpack for a long time. (Now I just need to invest ~40 keys to complete it...)