Multiple questions on Selling my property with owner financing

[Jason P.]

I have a duplex in Illinois that I'm thinking about selling with owner financing as it's a free and clear property.

Where would you post that? And would you do it on your own or get a broker involved?

Both units are rented out but upstairs said she is moving out soon. 

Downstairs 2/1bth $600/m

Upstairs 2/1bth $500/m

Property needs work and am asking $120k

What down payment would you suggest? And at what interest?

Was thinking $25k @9.5%. But what do you all say?

Thanks!