How to do you negotiate with a off market seller?

[John Moon]

I've been doing mailers and getting some response. However, I'm hitting a wall when sellers are not willing to negotiate their price. I tried getting them comps, and reasons why it would cost $X amount (even when units need work). However, they just say "no sorry this isn't going to work". 

I also tried getting the seller to do a seller finance and hold a note for a higher amount, but they're not interested in that either. *Maybe I'm not presenting the seller finance route in an attractive way.  

What are some tips you guys have when speaking with sellers?