He may realize the offer he had was inline with the value.

There are a bunch of ways to do this depending on the property type, usage, and you (income and credit scores).If this is a primary residence, you can get up to 90% of the value of your home minus any exisitng debt. 

My only concern is searching for the rent to value "1% rule". 

Are you buying amazing deals or are they closer to market value?  

You'll get a feel for the age of the neighborhoods, the vitality of the commercial buildings, the ease of location, the closeness to jobs.The markets you're describing are more linear, and usually have lower capital appreciation.

I focus solely on Detroit proper because, in my experience, the rent-to-price ratios, opportunities for value-add projects, and overall market potential are much stronger there.That said, Detroit is a nuanced market.

The number you feel would be enough to retire on will keep moving.

that we’ve learned in our 24 years, managing almost 700 doors across the Metro Detroit area, including almost 100 S8 leases:Class A Properties:Cashflow vs Appreciation: Typically, 3-5 years for positive cashflow, but you get highest relative rent & value appreciation.Vacancy Est: Historically 10%, 5% the more recent norm.Tenant Pool: Majority will have FICO scores of 680+ (roughly 5% probability of default), zero evictions in last 7 years.Class B Properties:Cashflow vs Appreciation: Typically, decent amount of relative rent & value appreciation.Vacancy Est: Historically 10%, 5% should be applied only if proper research done to support.Tenant Pool: Majority will have FICO scores of 620-680 (around 10% probability of default), some blemishes, but should have no evictions in last 5 yearsClass C Properties:Cashflow vs Appreciation: Typically, high cashflow and at the lower end of relative rent & value appreciation.

Rehab costs and ARV (After Repair Value) are key parts of evaluating deals, so it’s great that you’re diving into these concepts early.For rehab costs, creating a rough estimate starts with understanding the scope of work and local pricing for materials and labor. 

You could also get a line of credit for about $150k (you should be able to borrow 75% of the value.)The reason I suggest this is…1) you save $40-$60k in selling costs. 2) you have a lower blended interest rate (2/3rds at 3.25% and 1/3rd at 7 or 8% instead of the whole $500k at 7 or 8%) saving you another $1k/mo in interest. 3) you only pay interest on that $150k when you actually use it, not from day 1  Unless you hate this property, or want to buy something you can’t afford without selling, that would be my plan.