The two sources below can perspective into developing a purchase price as part of a lease vs. purchase analysis for the equipment in your acquisition. The first link is from a presentation posted on DoD's acquisition website. The second provides ideas for online calculators that perform the analysis.

https://www.acq.osd.mil/pepolicy/pdfs/DOD_OSD_Lease_vs_Buy_7-31-13_final.pdf

https://www.wsmr.army.mil/RCCsite/Documents/Lease%20vs%20Purchase/Lease_vs_Purchase.pdf