In the document, the ship's have the following prices:
Sil 6 frame is 1,000,000 credits.
Sil 7 frame is 2,500,000 credits.
Sil 8 frame is 10,000,000 credits.
So, maybe use those to develop the frame prices for space stations?
Maybe Sil 9 for 25,000,000 credits, and Sil 10 for 100,000,000 credits.
Just spit-balling here.