Steam is actually having a sale on Gta V right now and I am pretty sure it is $15 so I would recommend buying it their. Rockstar is still a great place to get it from though!GTA isn’t sold separately as far as online and off-line. Some people like to buy the media so they can share it with friends or family. I like buying digital copies because then you never lose them and you can always re-download them And nobody can steal them from you or borrow them
Rockstar games are the best in the world second to none and they hold their value so you’ll pay whatever the going rate is usually around $40 to this day