Lockout kits can be had for ~100 bucks, Fitting them can be a massive pain, as the rod ends are bloody tight.
What model Tien's were you looking at, some of them are horrid, some are good, I wouldnt go anything more than Super Streets for a street skyline, the rest of the Tien line up is mainly drift/circuit orientated, So not much good for Aussie back roads.
A Set of BC Racing's with some softer "swift" springs could be a good thing and probably still come out cheaper than the Tiens.
Or if you have the budget a set of "Aus Spec" Bilstein B6's with Custom springs to suit (once again Swift Springs are recommended to me by nearly everyone I know who races)
Then as a must have, get some aftermarket swaybars under the thing, will make the car feel much better than just some stiffer springs/shocks,
Big swaybars and soft springs is what works on a street car.