If you buy them during regular time (2x eBuck), I dont think there is
any limit and you can buy as many as you want
But, if you do a large purchase during eBuck promotion (4x, 6x, 8x, 10x)
from PPDG, there might be a chance that you will get banned. $500 usually is
OK, $1000
is kind of dangerous. So take your own risk.