I am not sure where you would get an appraisal. I think shelters are a good place to start, perhaps a show judge or reputable breeder?
Mixes are much cheaper than purebreds generally. In addition, your baby isn't a particularly popular mix or "designer dog" type, so I imagine there is no argument she is worth more to the market either.
I would say your estimate is going to be well under $400, but that is just my opinion. My girl is a Morkie and I didn't pay much for her at all and no where NEAR purebred yorkie price, and she's considered a "designer dog." (God I hate that term, but I will apply it here to make a point).
I would expect shelter price would be a fair estimate. Make sure you ask the shelters to appraise her EXCLUDING the vet care they give them, this would lower the price and rightly so because it sounds like YOU gave all the medical care. Also, please get reimbursed for any medical expenses that you should not have incurred as well.
I am sorry this happened to you! Remember to argue for the difference because they might make you return the pup for a full refund.
Also note: I would not recommend involving the legal system right off the bat. If you can get them to settle out of court, you may be able to get FULLY reimbursed (most people don't like legal ramifications waived in their face and may do anything to get rid of the problem). I would try bargaining outside of court first and then taking it to the courts if they don't comply. One caution about this method though!!!! Make SURE you know what kind of window you have to file a complaint, if you wait to long you may not have a case, so please ask a lawyer what your window would be.
I hope this helps some. Your baby is absolutely adorable though and I'm so glad she brings such joy to your life!!!! That is what really matters in the end.
