Can't remember my first rare but my first achievement was the UR tiger (I did a huge offsite with cs and fr for it) I was so happy at the time but I did not have the essential experience enough to know what it's worth and was taken advantage off by another user
It being worth almost 10 non and me tradeing it for barley 5 nons worth of pets
oh well I learned my lesson and am currently building up my collection to achieve one again or maybe I will get lucky and get one on the 18th lol well you never know