What laptop do you have specifically?
Initially reading it, I thought you were looking at a 32GB SSD + 500GB HDD.... in that instance, the SSd should be configured as a cache drive.
You've mentioned a 500GB SD Card though..... and those typically go for approx $300 USD.
While it's possible to re-map your drives/folders so they are stored on the SD card or HDD.... I doubt it would be overly economical to do so.
Most "laptops" with 32GB SSDs are glorified tablets... +$300 for an SD card.... you'd likely be better off buying a new (or "new to you") *actual* laptop.