It can actually be difficult to get an accurate estimate depending upon how far they are behind and whether it is in the hands of a law firm. I had one last year that was 1 and 1/2 years behind. The missed payments were about $1500 but by the time the law firm added all sorts of fees it was over $8000. I negotiated with the law firm to about $5700 but we didnt know how much it would take until closing day.
Hopefully this is not the case and as SD R stated, then it should not be hard to get a reasonably accurate estimate.
