Pencils
Gail Mechanical Pencil

There are a few “grail” mechanical pencils that are no longer produced and are all very expensive.
They can be found on Japanese auction sites like Yahoo Auctions and occasionally on eBay: Pentel Mechanica ($300+) Pentel QX 0.5 ($700+) Tombow Variable ($250) Faber Castell Alpha-Matic ($100-400 depending on body material) Pilot H-5005 ($300+) Pilot Automatic ($300+) Staedtler Micromatic ($200+)
However, I consider myself a vintage collector and I haven’t bought any of those pencils yet (way too expensive!) I think a better approach as a collector is to just look around and buy the pencils that personally attract you the most. A lot of those grail pencils aren’t that expensive because they really are that much better than other vintage pencils made in the time period, but simply because of the reputation that they have gained in Japan. If you want some cheaper vintage pencil suggestions, one of my personal favorites is the Pentel Accugraph line, with the PG1505, PG1804, PG2003. It has a full-metal body, nicely knurled grip, and looks awesome. If you look around on Yahoo Auctions or eBay like how I got my PG2003, you can find ones for under $50 and it is just as good as a lot of the much more expensive vintage pencils I listed above.
If you want more choices, a good option is to browse some old catalogs and see which ones jump out at you. Here’s a 1980 Pentel catalog for you to get started: http://yyjj00.tistory.com/11