
Is there 3 different mastiff breeds- Mastiff, English Mastiff and BullMastiff?
There is only two the Mastiff and the Bull Mastiff, most people know the Mastiff as the English Mastiff.
They are docile, and very good with children, but as with all dogs should be well socialized as puppies.
Yes they do come in brindle, and can be several different shades of brindle, you can have dark brindle, apricot brindle and also a light fawn brindle colour. The K.C here have not long changed the colours, and now brindle is just classed as a brindle regardless of shade.
As for price it varies here, as to what people charge but, my advice would be find a reputable breeder, and if possible always visit the kennels and meet some of their others dogs.
Good luck in your search.