Requires Unity 3.5.7 or higher.
Modular spaceship pack. It contains 35 spaceship "modules" that you can use in the unity editor to create your own designs. There are 3 spaceship styles, each style uses 1 texture map. The individual modules are a few hundred tris max (each is different), the example ships are 2-3 thousand.
15 pre-made ships are also attached, to give you an idea how to use the modular elements.
NOTE: spaceships made using a lot of parts can be draw-call-intensive, so it can cause slowdowns in mobile platforms. There are numerous ways to battle that, either using dynamic batching, making it one mesh in a modeller program, or using an unity plugin like Mesh Baker 2. The example ships are already combined to one mesh in a 3d modeller program.