Chris Aldrich has bought some index card cabinets:
I just did a quick calculation and I’ve purchased 2 large card index cabinets, and 5 small indexes […] It gives me about 65 linear feet of index card space which should hold approximately 108,000 index cards.
Buying cards in bulk groups of a 1,000 for the going rate of about 2 cents each, I’m looking at a lifetime index card bill of around $1,700 to fill it all up.
If I look at a 30 year time span, I’m all in for about $2,500 (I’m adding a bit for pens/pencils/ink) versus an annual subscription to Roam Research (currently $165/year) or for Evernote (currently $170/year) both of which would put me at about $5,000 (presuming either is around in 30 years.)