Oregon is a different market than much of the country, so metrics like ROI and cash on cash come down to your personal preferences and goals. They cannot guide you on what the value of the property is in this market. If you're concerned with what it's worth to you and how it will help you achieve your goals, then analyze the metrics that are important to you. If you're wondering if the offer is a fair market price, consider having an appraisal done.
If you don't want to pay for an appraisal you could create your own estimate by using an average of online estimates that are available. I use Zillow, Redfin, Realtor.com, and the county assessor's website. Don't use Trulia because it's exactly the same as Zillow.
Lots of people will tell you to ignore estimates from Zillow and other sites, but if the property is a typical house on a typical lot in a city with lots of comps, it'll be in the ballpark. My personal residence has a Zestimate of $252,000 and I just had an appraisal done that came in at $259,000, less than 3% off.