It's been a while since I bought villagers but it can be tough I feel like it's easier now that people have the cards (so you can request them) and there are lots of cycling towns. I had a really tough time getting some of my villagers in my old town (like Katt and Amelia). I never did get Nan or Tabby because the timing was always off.
It's also hard to give away unpopular villagers... again, it seems like the timing is always off.