Collectors collect things of a specific type, professionally or as a hobby. As a hobby, the collector gathers what they find interesting and which provides them with enjoyment. As a profession, the collector acquires items as an investment anticipating that its value will increase over time. Special terminology is used to refer to collectors who have a common interest in a specific type of collection. I've listed a few of those terms below just to give you an idea of what is considered by some to be a "collectible". Note that the combined letters "phile" derive from the Greek word "phileo" which means "loving" or "lover of", and the combined letters "ist" indicate a person who practices, specializes in, or is concerned with a certain something.
Arctophile: someone who collects stuffed animals/characters.
Arenophile: someone who loves the variety of colors, textures, and mineral compositions in beach sand and travels to different beaches to collect samples.
Deltiologist: someone who collects postcards. Collectible postcards are usually referred to as ephemera which means "items of collectible memorabilia, typically written or printed ones, that were originally expected to have only short-term usefulness". Some deltiologists collect all postcards and others choose to collect only postcards by specific artists, publishers, location, or time period.
Lotologist: someone who collects lottery tickets.
Panelology: the collecting of comic books as artwork.
Pannapictagraphist: someone who collects comic book collector.
Philatelist: someone who collects stamps.
Phillumenist: someone who collects matchboxes. Note that this term contains the word "lumen" within it which means illuminate.
Plangonologist: someone who collects a wide spectrum of dolls.
Sucrologist: someone who collects restaurant sugar packets.
Tyrosemiophile: an avid fan of the humble cheese label.