When you're dealing with (I don't know a better word) "good" folder hardware, if its advertised as 1/8" it actually going to be .0005" under that, meaning that it will fit into a 1/8" reamed hole. I don't know were that hardware is made, but I can tell you from past experience that IF the hardware is made in China, its a crapshoot..... I've had pins and pivots that were suppose to be .125" (advertised as 1/8") and some were 2-3 thousandths larger or smaller then advertised. This makes things really difficult, and makes me very grumpy.
If you're talking about something like a hardened dowel pin, my recommendation is to look closely at those sold by Enco, checking to make sure they are U.S. made, and buy a package of 100..... its going to be a lot less expensive, then just buying a few loose ones from any knife supply outfit, and IF you buy U.S. made, and the knife outfit is selling China made, you're going to be far happier with what you get.
Personally, I buy nearly all of my folder hardware from Steve Kelly at TiConnector.com. Everything is made here in Montana, and Steve strives for zero tolerances on all of his parts. It took him a year or so to get me to try his hardware because most of it is Titanium, and therefore expensive when compared to the made in China stuff......but it is WELL worth it! For lack of a better way to say it.....with made in China hardware I would always have to fiddle and fuss with my folders to get them "right", because the tolerances were so wide......when I started using Steve's hardware, my folders just sorta "fell" together, and worked.....haven't have to fuss and fight with one since.
If anyone has ever used made in China folder screws, only to find that the heads were not concentric, and the heads wouldn't fit in your counterbores......no such thing with Steve's stuff. I'll go out on a limb and say that Steve makes the best folder hardware available. If you want to stop fussing and fighting with building folders.....the first step is to start using Steve's hardware.....its that good.