Spine offers different licensing options, but there isn't a specific "indie" or "solo developer" discount beyond the existing tiers. The Spine Essential license is the most affordable option, priced at $369, and it provides the basic features needed for creating animations. If your studio's revenue is below $500,000 USD annually, this license is sufficient for using the Spine Runtimes in your applications. While there is no specific discount for indie developers, you can start with the Essential license and later upgrade to Spine Professional if needed, paying only the difference in price.