I think my top picks have been for personal use rather than resale.
I mean, I've gotten home speakers for $20 and sold for $300.
Set of brand new escalade rims and tires for $100 and sold them for $1200.
And that rotary tool I got about a year ago for $15 and sold 45minutes later for $225.
But mostly the thing I remember are items I want/need but can't afford then find cheap at a sale.
Like the $300 carpet cleaner I got for $12.50.
I'm building a set of copper cookware. Have $400-$500 worth now and have spent $50-ish.
Or the Tiffany&Co cheese knife set for $40. I'd never spend (and think its crazy someone spent) $695 on something like that but $40? Yeah, it adds something to the meal to have a nice set like that. (Tho if I ever need money I'd have no problem selling it!)
And just last week I paid $20 for the contents of a pantry (estate sale).
Had jars of pine nuts, saffron, truffle's, really good olive oils, imported olives of various kinds....quick calculation it was over $300 in stuff I love but just can't justify buying it.