I think it was an impulse buy during the biggest sale of the year at my favorite electronics store.  Everything you can fit in a supplied paper bag is discounted by 20%.

The item in question was an Adafruit RGB LCD.  I soon realized that I should really have one of their RGB LCD backpacks to drive it, since the 18 pin layout is different from a standard LCD.  I looked on their web site and was disappointed to see that the backpack was only sold with a LCD, so the display went into a plastic bin.

Some time passed and I had the idea to ask Adafruit to sell me just the backpack. I wrote an email explaining where I purchased the display and my predicament.

I would like to buy the serial backpack for it but you do not
seem to sell it standalone.

Could I buy one?

I received a quick reply from Adafruit customer service.

Thanks for the note. We do not offer that product for sale as a stand alone product at this time.

The display went back in the bin for a full five years, then one day I stumbled across it and returned to the Adafruit website.  This time I noticed the schematic for the backpack, it is built around the MCP23017 IC.  In no time flat I was able to find a breakout board for that chip on eBay and seller cctv008008 had no reservations about selling me one.