Single unit, Limit to 3 unit(s) per customer. https://www.cytron.io/p-raspberry-pi-rp2040-dual-core-microc...

You really don't. That's a small reel, most resellers are making it available in cut tape (single unit, or 10 chip) quantities. 500 and 3,400 unit reels will be available later in the year (in the autumn). They aren't generally available now.