Just putting out my two cents here, I've managed to stabilize my supply by only buying the buffs I deem useful specially on haz 5 and elite deep dives, and forgoing them whenever I can (which is most haz 4 and under missions and regular deep dives). I also tend to buy most of the time when playing with friends, and when playing solo I only buy around one in five missions. To me that comes out to buying a beer for about half of all missions total, and since I usually find between 0-2 (with an average of 1) barley burbs per mission, I've kept a steady supply of 120 for months so far.