You should also consider the fact that prices can also be determined by the seller's discretion.

Sure sure ofc I'd never forget about that, but it isn't the norm to find someone who sells for cheap. But ofc it happens I know this. And although the property you bought is residential yet cheap, I'm still pretty sure it's located somewhere in the outskirts probably bordering agrliculutral zones or provinces that's why the owner is willing to sell that property with a zonal valuation of one.

The gist is property prices vary and there are no concrete prices. Land classification, seller discretion, area and even judicial factor may set in to change those prices. OP's (if not prohibites by law) can buy any sort of land with his budget and assuming that he spends the time to look for the best deal, he can find options that are really cheap.

Yeah but still to suggest that you can purchases a mansion for 20M is naive. If you can get one, sure go for it. But I will reserve my questions about the quality, state and location of this "mansion" of yours.