TRU is notorious for being up to $30 over WM and Target prices on Lego sets. I was in there Sunday and they still had some Harry Potter Hogwarts (4867) sets which retailed for $49.99...TRU had them for $79.99. Even when it's not the holiday season, TRU is still way over the odds on sets.
I think they do it because, like Diddly said, they can be the last stop for people that find stuff sold out at WM and Target, plus they carry a lot more inventory than either of the other two. They have the mindset that since they're really the only toy retailer left, on a large scale, that they're a destination and people will pay more for the experience.
E...