I have a new testament bible.from 1878 how much can I get for it??

First is it just the new testament or the entire bible.
Next how have you determined the actual print date, ( not just copyright date)

What version is it, a Kings James, or a New Greek version.

What is the condition, the cover. Is any family history printed inside. Is there any documents putting it with any certain owners ?

And to give you an example, here is one for about 80 dollars Antique New Testament Lord Saviour Jesus 1800's London | eBay

Unless something makes this one rare, most likely it will not even bring 80 dollars unless it is somehow in like new condition and be real.