Event birds you can only get them when the event is on. You could end up spending a lot and not getting them if they are 2nd or 3rd bird. Few of the regular 5-stars are sort of rare. It took me more than 12 months to get Steve and Dutch. In the same time anyone can easily build an army or all Carson or all Zain. Meanwhile the silence from Rovio on FB is deafening after the event rewards NERFing.