NOS tubulars are still readily available with a little patience. Having a preference is the difficult part, like Mavic CD 4's. I have been collecting them for the last 10 years as they come up on CL or other sources. I now have a supply to lean on and likely some to sell when I can't ride anymore.
Found this lot for about $75 for all of them.
IMG_20200219_122706 on Flickr
A number of the ones on the left are Mavic GL330, which I thought would be hard to find. They just showed up several times and I snagged them. My Colnago had them with Mavic 501 hubs. Great combination.