I believe it was just a flat rate per property per month, and quite inexpensive.

You are just as likely to have the rates climb while you wait on this subpar company as you are to get a better deal.

I am in Missouri right now staying in cheap hotels for work, I got out here a month or two ago and the plan has been to buy a property, preferably a duplex.I did pretty well selling solar last year and have saved up some cash to use as a downpayment for the first property.

The recent interest rate hikes have taken a toll on this deal for me; however, because now my lender is telling me that because of the changes, I need to pay off more debts to make the deal work.

I have a great interest rate at 2.64%.

I'm basically looking for the following fields (or whatever I can get):- Median Sales Price- Median Rent- Vacancy Rate- 5 or 10-year Property Value Appreciation Rate- Any historical values for the above to compare against currentAny tips/bits of wisdom folks can share would be appreciated!

One last challenge is their estimate of property taxes - they are all VERY low:(Michigan has some interesting property taxes because there's a Taxable Value and a State Equalized Value, as well as Homestead and nonHomestead millage rates. 

Practically what you will earn from participating in tax sale auctions is an interest rate of return.

What is the going rate for a 3 bedroom detached?

You are heading in the right direction to get the financing options laid out and then find the deal so you can pull the trigger for the right one.As far as HML options be sure you get all the details before signing anything . . interest rate, payment terms, what if you need to extend, points up front, etc