It may seem a bit counter intuitive but DIY rarely comes out ahead in money saving. When I was less experienced, I rarely considered the value of time I spent pursuing DIY builds. I think if you factor in tools (especially if you haven’t already invested), failures, shipping delays, troubleshooting, studying documentation (or lack there of) etc. the small costs, and setbacks, I rarely break even over a retail version.
That said, I am a continual DIY hobbyist and I am not planning to stop DIY builds. There is tons of value in it, understanding the technical aspects of the synthesizer, or contributing to an open source project/community. Also consider patronizing small synth builders directly (if it’s possible for you to do so)!
Not all DIY is made equal, my personal preference is to try and find projects with PCBs with SMD parts pre-soldered (this is after investing in work bench tools to do exactly this) The Norns DIY, and Fates DIY kits are examples of DIY done right.
I guess I would caution that “DIY will save you money” isn’t entirely accurate advice.