I have seen quite a few of this cross breed around and the average price seems to be around the 350/450 mark as said before most of them look nothing like chihuahuas.
Its not just poorly bred chihuahuas who have moleras, most moleras close when the pup is a few months old, some chihuahuas have permanent moleras which persist into adulthood.
Heart dieses is more offen found in older chihuahuas so it is something to watch as they get older.
Like said before Haemophilia, a blood clotting disorder carried by the females and manifesting in the males, also occurs, also things that when looking at the pups parents is Weak knee or patellar luxation (dislocation of the knee cap).