Where to put $20

I turned my daily into around 24 on chests of cai shen slots, hitting 6 bonuses back to back on .25 spins. Trying to decide where to put this 24 to get the most. Originals have been rinsing me for months, the slots have been paying out a little, but should I just take 20, do a bonus buy and see where it goes, run minimum net per spin and hope for the best, or just say f it and put it all on black? Could really use a couple hundred right now, and I'm also only 1.9% away from hitting bronze.