I assume you are negotiating with Phoenix and Koda? I have NMA in the same township in sections to the East. We have signed a few leases recently in 159 R103.
All have been 4 years with 2 year extension. I haven’t heard of anyone getting a 3 year lease recently.
Depending on how important your acres are in the Drilling Unit, you can definitely get more than $500/nma. I assume your DU will include Sections 6, 5, 7, 8, 18 and 17. The will run wells in a 3 mile lateral, likely a few legs covering those sections.
Have you let them know that you are talking to the Landman representing Phoenix/Koda/whomever? Make sure you don’t mention the $ amount, make them offer an amount. Be patient, and wait for them to come back. Also, all of ours have been 20%.
Good luck with a lawyer. You might have better luck looking outside of Williston, most are all booked or already representing the Oil Companies.