How to value note?

[Tom Burns]

I write lots of paper via self-directed IRA, typically for flips, but I also hold a $50k 2nd on a small commercial property. I am 12 months into 60 month balloon, interest only at 9.6%, $400 per month. 1st position lender is same terms as me and has asked me if I am interested in taking him out. Obviously would like to buy it discounted if I can, but have never bought a note before, no idea if this warrants a discount? Both loans are current, all direct deposit from borrower, property value around $200k.