I also noticed that Wu Jin Pen has a “Buy Bonus” button.
It seems like the pricing on buying a bonus would be flexible or meter-dependent, i.e., it should cost you more to buy the 50 in the picture than it should to buy a 5 right after you knock off the 50.
I am going to have to wait another 24 hours before I can investigate…can anyone confirm that pricing on Wu Jin Pen “Buy Bonus” is linked to the meter number?