I'm not sure when you used it, but Houdini Indie[1] looks pretty reasonable- $200/year and you don't have to upgrade until you're doing $100k/year in revenue.
[1] https://www.sidefx.com/index.php?option=com_content&task=blo...
[1] https://www.sidefx.com/index.php?option=com_content&task=blo...