There are certain things associated with tube production that aren’t available now mostly due to environmental regulations
This is true. However there are some current production tubes that are very high quality with commensurate cost. I can personally attest to the construction and sound quality of the EML tubes manufactured in the Czech Republic.
I purchased a new pair of the EML XLS 300b in the spring of 2013. I have used them very regularly (9.5 years) and they tested strong on an ampltrex tube tester 6 months ago. They continue to sound superb.
So, depending on commitment and resources, very high quality tube production is fortunately still possible.
Charles