Thanks John! I never considered the possibility of a vacuum leak actually sucking the brake fluid into the booster.
It sounds like sending my booster and master out to be repaired is the cheaper route. I'll give them a ring and compare prices.
For anyone else in a similar situation the prices on the ebay listing I mentioned go like this:
Rebuilt master and booster: $650
Shipping to me: $30
My estimated cost to ship my old core back to them: $20
Core refund: $250
Final total cost $450