[ramenbytes]

- Digikey

- Mouser

- SparkFun

- Adafruit

- Antique Electronic Supply

- Sphere Research Corporation

-Ebay, occasionally, if the seller is trusted and known by your corner of the electronics community.

There are several mailing lists where you can get equipment and parts as well over on groups.io.

- test-equipment-buy-sell-exchange

- tekscopes

- hp-agilent-keysight-equipment

and other sources that I'm not remembering off the top of my head. Check out the EEVBlog forums, they probably have a list somewhere, or can tell you where they shop. Same with the various mailing lists. If they don't have it, they might be able to point you towards who does.

[dghlsakjg]

MicroCenter is good too, especially if you can go in person

[tyingq]

A little more niche, but tindie.com also.