Hi, I have an experience in texturing and preparing 3D assets for Unity3D. I can provide You with final planes with only 1 material, or if you need transparent windows 2. With the resolution of the textures, that You've mentioned there will be no need for more to achive very good, detailed look.
The price, that I'm puting up is for all 15 planes, so that would be 10$ for a single plane.
Contact me please on the job details, and feel free to ask me anything.
Best Regards
Marek