Most of the currently published systems of note have PDF or electronic versions for purchase (although the price varies from "much cheaper" to "the only reason I'm buying the PDF over the hardcopy is that I want to specifically put it on my computer/tablet and use the Search feature"). A large amount of the GURPS 3rd library is available for cheap, I know I've gotten a good deal on a bunch of Pathfinder PDFs through Humble Bundle, and while it requires Fantasy Grounds (which brings us up to "spending as much as on the hardcopy books" and limits us to PCs) or their first party site DNDBeyond, even D&D comes in electronic form these days.
"You know how parents tell you everything's going to fine, but you know they're lying to make you feel better? Everything's going to be fine." - The Doctor