Last year they did a “November to remember” early sale:
https://forum.xojo.com/t/ann-early-black-friday-sale-get-20-off-on-xojo-licenses/
Just keep an eye on the forum and subscribe to their email announcements as the sales usually are just for a few days. If I want to be sure to buy during the next sale I may email hello@xojo.com to make them know and add my email to their list.