I’ve used vxb.com for bearings for a long time. (No affiliation other than as a customer.)
When I buy from there, my PayPal charge comes back as “Nation Skander Inc” but I’ve only ever known them as VXB.
Their search by parameters is OK, but they often have “multi paks” that don’t show up in the search. For example, 10 bearings that are 3x10x4 mm (3mm inner, 10mm outer, 4mm height) for $12.77, whereas a single bearing is liseted at $5…
They also have fancier ABEC and ceramic and such bearings – at fancier costs, of course.
These bearings take an M3 bolt with a small amount of slop, or a 3mm dowel pin with a press fit. Great if you have small things that need to articulate, or for keeping your BB feeder agitator centered in the magazine cavity