What Makes a Zine Collectible?
Rarity, personal meaning and research value are different reasons to keep a publication.

“Collectible” can mean several things. A zine may be difficult to find, connected to a particular person, useful for research or simply important to its owner.
Those kinds of value do not always coincide. A copy can matter deeply without being expensive, and a high asking price does not explain why the work is worth reading.
Start with the reason for collecting
If you want the writing or art, a later authorised edition may serve you well.
If you are studying how a publication originally appeared, the first printing may matter more. Paper, dimensions, changes to the text and included material can all become part of the question.
Decide which purpose applies before treating one version as automatically preferable.
Scarcity needs context
A small print run does not tell you how many copies survive or how many people want one.
Likewise, a seller describing something as rare is making a claim you can investigate. Ask which issue or edition it is and what evidence supports the description.
Avoid turning “I have not seen another copy” into “there are no other copies.” Personal experience of the market is incomplete.
Association can be historically useful
A copy may connect to a maker's early work, a particular scene or a recipient who kept related correspondence.
The useful word is provenance: the documented history of an object's ownership or origin.
An inscription or envelope can help establish a connection, but the connection should be described precisely. A name written in a copy is not, by itself, proof that a famous person owned it.
Condition is more than appearance
Check whether the publication is complete. Are there missing pages, detached inserts or alterations? Is the copy an original, a later printing or an unauthorised reproduction?
A worn but complete copy may answer your research question better than a cleaner copy missing a crucial section.
Record the condition you observe instead of relying only on broad labels such as “good.”
Libraries value material differently from markets
The collection-policy guidance at zinelibraries.info explains how a library chooses a focus and decides what fits.
A publication can be valuable to a collection because it documents a community or subject. That is different from predicting resale demand.
For your own collection, the equivalent question is: what does this copy add?
Buy with a clear purpose
Set a limit you are comfortable with, compare the description with photographs and ask about unclear details.
There is no need to treat zines as an investment. A collection built around reading, research or personal interest gives you a reason to keep the work independent of any future price.
Next: How to Start Collecting Zines.