patio said it!
The computer shops eventually stop saving more screws, after +-10 lbs. Or 5 kilos +- for the metric ones!
I would say the ones in the pic top row far right are usually the ones, Take the standoff to the comp shop with you, , , , They have to 'get rid of old comps after customer upgrades, ask them if they have one (minus any hdds, natch') take it apart & keep the screws!! (mobos to the recyclers, right!)
-c-