To this point, are there any free/cheap apps/browser apps that clone simple/older/well known synths you'd (or others here) would recommend for skilling up a bit? Doesn't need to be anywhere near pro quality sound-wise, not what I'm after.

A million years ago I had some analogue korg model and have been interested in playing around again. But I know myself well enough to know that my interest may very well be fleeting and I don't want to invest much in the way of $$ to go that route.