I buy moondollars when there is a reasonable fall of the price. If the fall of the price is near the common ups and downs of the price, I will not buy any. Other than that, I do not buy moondollars regularly because I earn it. 
I sometimes do that, if I still have spare money, I grab the opportunity when the price drops more than normal, say about $20 drop, but now, I think it is good to buy when the price drops atleast $5 and same as selling..
Yes i also think it is the time to buy because price is very much stable and it is not going down and it feels like it will go up after some days....