The first thing to remember is that not all Pragmatic Play slots have a bonus buy feature, if they do it can also be down to the casino whether this option is enabled. This ensures the slots remain legal in certain jurisdictions where the Bonus Buy mechanic is prohibited. If the slot does have a Bonus Buy option this will be displayed clearly to the left of the main reels, clicking the button will confirm the total cost to buy the bonus feature and this is generally based on the current stake level, with an option to increase or decrease the cost before confirming the bonus buy. As a general rule, the bonus buy cost tends to be 100 times the current stake level, but if the slot is particularly volatile with a rewarding bonus feature the cost can be significantly more.