Windy's fine tuning service
Windy is listed under Recommended Clarinet Tech Services.
For $600, Windy will buy and C or A clarinet from this manufacturer for you, fine tune it, and then send it to you.
OR, he will fine tune a similar quality newer model Chinese clarinet for you for $400.
The 'fine tuning' includes more than just intonation, but complete regulation of the action and many other improvements.