My mini top has a whistling noise when I get to around 35-40 mph (and above). This is coming from where the top meets the windshield. The rubber weatherstripping looks fine, and the top appears to be fitting snug. I tried cleaning everything up super well, and also using a "rubber seal conditioner" I picked up on Amazon for supposed sealing issues. If anything, it appears to have made the sound worse.
Any insight or next steps would be appreciated. I'm hoping to avoid completely replacing the weather seal, which seems to run about $450 everywhere. :(

Are you certain it is the window strip and not the convertible roof itself? I get the same whistle, but it is my roof. If I crack it open just a touch, it goes away. There are threads on here explaining that the motor is off just a little and all you have to do is take the cover off, and realign the guides for the roof. Check the other threads as they are more explanatory.
If it actually is the weatherstripping on your window, you might want to check a junkyard. In fact, two new vehicles just hit my local yard this week. You may be able to salvage something there.

The convertible top needs to seal the same all the way across or it will whistle. Some people have the sunroof portion not adjusted or a cable is broken.

https://www.northamericanmotoring.co...oof-opens.html

https://www.northamericanmotoring.co...nt-of-top.html

https://www.northamericanmotoring.co...placement.html

https://www.northamericanmotoring.co...eaking-in.html

Gummi fledge if the seal is uniform and gap is the same across, and the sunroof portion is fully closed.

https://www.ecstuning.com/Search/SiteSearch/gummi/

Well, I end up solving this the old-fashioned way. A 1/2 inch wide (and 1/8 thick) strip of black weather seal on the top edge where the convertible top presses against the plastic. You can push it down mostly inside, and you can't even see it. Solved for $6.