[ Ref. Jon Page in 240220 MMDigest ]

Jon, Victor Machinery is my "go to" for non-standard taps and dies.
They are often quite reasonable on price. A 4-32 tap is $11.10 and
can be found on this page: 

https://www.victornet.com/cgi-bin/victor/productlist.html?subdepartments=Special+Thread+Taps:618%2C1170%2C1171 

And a 4-32 die is $11.40 and can be found here:

https://www.victornet.com/tools/Special-Thread-Dies/198.html 

Hope this helps! 

Kyle E. Nasman - Nasman Machine LLC
Portland, Oregon