Just reading the thread again... the op had her dog on a leash and the larger dog that lunged and landed on her yorkie was NOT on a leash. 
That does put a little different "spin".. I think the owner of the big dog should pay all of the vet bill... and maybe some consideration toward a new pup.  The owner for the big dog should get "ticketed" and "fined" for not having her dog on a leash... or at least that would happen in Florida     
 BUT... I don't think the "potental" income and high end t-cup yorkie would be the way to go.  OP you did not pay for the pup.. it was a gift correct?  I don't think you are going to get money for the pup..   
I am so sorry.. this has to be hard for you.     
				__________________  Shinja  mom to   Remy   lil Sis to     Bailey and Sammy        |