You are not even scooping your initial investment so your cash on cash return is negative.

Quote from @Robin Simon: Quote from @Jonathan Greene: To me, cash only is just cash.

(You say it’s worth about $100k more than you’re paying so figure an extra $15k.)Maybe you’d be better off partnering with the parents unless they have zero interest?

Do this quickly because some counties have a time limit on when you can appeal.I recommend you research the market for:- Comparable Property Sales- Condition of your property, including anything that may affect your property's value- If you are really serious, an expert appraisal may be worth the effort.

Your son is likely paying more than the property is worth, by definition, as the seller would almost certainly prefer a similar offer that was not subject to. 

Most ideal would be seller financing, but open to creative strategies for a cash-flowing property. 

Seller won’t budge on price and it will be tight for cash flow.

First of all @Diana Teng, have you ever gone to a restaurant and asked "is the food here worth buying?". 

We were just happy our first and second mortgage was going to be covered and have a little cash flow at the same time.

Germantown has better cash flow potential but may require more hands-on management.