If your only goal is “spend the least money possible,” SayCopyPaste is not the cheapest option and we won't pretend it is. There are good open-source dictation tools — built from source they cost nothing — and several of them also process audio locally on your machine, which SayCopyPaste does not do today (an on-device mode is (planned), not shipped). If you're comfortable building and self-managing software, or you require local processing, those are honestly the better fit.
What $49 buys you over the free or open-source route is a signed, notarized, no-build install that updates itself, clipboard-first behavior that works in every app, vocabulary learning with one-tap correction, and the same managed tool — with synced history on Pro — across Mac and Windows. That's the trade: a little money for zero setup and one cross-platform license.