I've been playing this game for so longg and occasionally I also TT but still I've yet to unlock Katrina's shop lol gahhh I just want to complete my main street!!
You have to have your fortune told 20 times, I think, to get it unlocked. I just recently unlocked it and I will probably build it, just to have a completed Main Street, like everyone else who has it in their town. To be honest, I never kept track of how many times I had my fortune told and I prefer getting it for free via the Lovely phone, so I was surprised that I finally unlocked it.