I've been collecting navel fluff (just my own) since 1984, and upon learning of this, people usually ask "Why?". To this I answer "Why not?". In my mind, the worth of any collection depends on the following factors (in which my collection rates well):
* Uniqueness - millions of people collect stamps and coins, but as far as I know nobody else collects navel fluff. That makes my collection unique!
* Rarity - the navel fluff of Graham Barker is produced in very limited quantities by only one person and is not easily obtainable by others (not that anyone would want to).
* Completeness of collection - I've been collecting my navel fluff consistently for around 20 years and have seldom missed a day's harvest. This makes my collection almost complete, a bit like having the full set of a country's currency.
* Good condition of items - like uncirculated banknotes or stamps, my navel fluff is in mint condition. When harvested, I remove any body hair from the fluff then store it immediately in a jar, where it remains uncontaminated.
I've thought of doing this, but never did. Now... I don't have to.