Yeah it's Unity
To compare you can find some war threads like :
3DGS Vs T Rex Engine
or others !!

Friendly_Frank :
Yeah, it's cheap , but lonewolves no :
caus i'll never sell a game ,not my goal , so 1500$ to have top notch tools to play and have lot of good time ... hummm .. perhaps no

But for serious teams like the ones that maked a game with Unity , yeah indeed,
if you're sure to sell something , it's THE ENGINE