Before we get too into prices, realize you get what you pay for.
I sold my factory A body 8.75 right out from under my show car for 1,000.
When I quoted the prices for my dana vs. an 8.75 from strange realize they were both being built to the same specs and ability.
My dana from strange is powdercoated, narrowed, billet yoke, S-trac (eaton tru-trac) Willwood discs, aluminum cover with bearing supports. Most likely a few other bells and whistles I can't remember. They said it's good for 1,000hp all day. Shipped to my door that was in the 3k dollar range. They quoted me 5200ish for a similar 8.75.