How do you like to keep track of your purchases?

[Krafty]

My earliest sheets were in pencil, but after seeing how hard it became to read my earlier pencil writing papers I wrote everything in pen. Pen markings last a lot longer than pencil. Pencil marks only smear over time (even if it takes years and years to become noticeable)

I believed that pencil was the only medium that DIDN'T fade over time, pen was the type to fade away. I heard this on a TV show where they valuated some Beatles memorabilia, but maybe it depends what material the pencil is used on?

Well, as for making my own records, I do keep a detailed account on the top series I collect from. I save all the images of items I've won/bought or even had a interest in. This currently equates to nearly 17,000 images organised into folders based on title.
With the series I'm particularly fond of I add these details into the image properties- Date, Price, Seller, whether I aquired it or not- (if not I add the winner's username if possible), Runner-up username, Number of bids.
Yeah, it may seem excessive but it's fun to look back at the records to come up with bidding strategies or get a feel for what's hot or not at particular times.

[Keropi]

I believed that pencil was the only medium that DIDN'T fade over time, pen was the type to fade away. I heard this on a TV show where they valuated some Beatles memorabilia, but maybe it depends what material the pencil is used on?

What I meant was pencil smearing not pencil fading. Pencil marks smear over time. That's why it's not good if you have sketches or autographed pencil writing and it's moving around too much inside of its holder. The pencil marks are getting smeared. If pencil writing is moving around a lot inside of a large cel folder for example that's not really a good thing for it. At least put it inside of a bag so the pencil marks on the surface of the paper aren't getting brushed across so much.

[Krafty]

OK, Keropi, my mistake, I see what you're saying. It is annoying to have pencil smears and that could only be worse with a soft pencil. I guess soft pencils are used more often too because they give a darker/broarder tone.