The county auditor is the one who sets the house value.

I looked up the owners on auditor's site, and it says owned by "Selene Finance Lp". 

They're still possible but banks and their auditors tend to frown on seeing an investor doing too many of those.

Not a lot of room to maneuver.What is the current County Auditor's appraised value - if the sale price is a lot higher than the Auditor's appraised value - you could be in for an unwelcome tax hit.$55,000 per unit seems high for a C+ property in Michigan. 

The local county auditor's site usually has the actual tax amount. 

A couple of points with your numbers first is on Property Tax you should really check the Franklin County’s auditor site for the latest assement values.  

Cutting to the chase....I purchased a commissioner's certificate through Zeus (Henry County).Without getting too personal, I need to sell this certificate at face value.Redemption period expires 8/3/18.Now, certificates are assignable through the auditor; question is, where is the best place to find someone to take this off my hands?

Based on this info and my understanding of IRS rules, I believe just using the $149,500 number is safe since it's a little less than than the FMV and it's easy to trace back if the auditors ever come knocking on the door. 

But maybe if you owned them free and clear and it's $700/unit per month (just making up numbers if you're in a nice part of Philly) which is ~$34K per year it might "smell" a little different to an auditor. 

I'll preface by saying I'm a CPA but don't let that fool you as I was just a former auditor with probably no more expertise in taxation than the average Joe.