First of all...
You can buy the Criminal Enterprise Starter Pack for $9.99 it includes a Bunker as well as multiple other properties including a CEO office and MC clubhouse.
What you should work on buying is an arcade as that will enable you to run The Diamond Casino heist which is the best heist in the game since it’s inception.
If you don’t want to purchase CESP you can join The Diamond Casino Heist vía quick jobs on your phone.
If you are lucky the job host will be generous and give you a substantial cut.
This heist has the best payout in the game and can easily be accomplished in 15-20 minutes.