you can use the Nissan Primera ones and they are exactly the same for the skyline.
They are a little bit thicker than the Nismo ones but hey they are like a 1/4 of the cost if not more!!
me and PMJ have them and they look the biz mate.
The only thing to point out is that when you use the primera ones (or whatever the damn car is!), they are not as pure white as the nismo original ones. You can see the orange bulb more through the cheaper indicators than the original £150ish ones.
Just my 2c worth! (.... I have the cheaper ones and am happy because I think they are value for money, but just wanted to point out that they ARE different from the expensive ones).