What do you do to take into consideration the SUPPLY side of things in these newer/growing markets?

This is a general discussion question...I am curious as to where you get your data, as a Broker nand an Appraiser, I would think that it is critical for the fix and flipper, buy and holder, wannabe wholesaler, or general investor to have MLS access...do you also preview what is on the market when attempting to make a rational investment decision in order to have a strong ARV as well as an understanding of what others are supplying in the same price point, ie. the competition, I put zero credibility or credence in Zillow, yet I see so many people placing emphasis on this weighted algorithm...understanding that this is a big country with many different markets, I am curious to hear your feedback.

Sure you will have multiple tenants vacate and possibly trash the house, the HVAC need replacing, the roof start leaking, toilet or water heater supply hose burst and flood the house, termites infest and swam the house, lightning hit the tree next to the house and blow out windows, neighbor burn down your fence, tree fall on your house, the bank close your line of credit for no apparent reason,  insurance company you have used for years drop all your policies at once without ever having filed a claim. 

Half goes to the broker before you pay for gas, supplies, dues, etc. so 54,000 to you.

Ask the seller to be an equity partner in deal by supplying the 20% down payment.  

Its hard to discount a general slow down in appreciation simply due to the economics of increased supply, but will I really lose a lot of value or have trouble selling my condo if in fact the new product is simply a different market?

Turn key companies get substantial volume discounts on supplies, materials and mechanicals.3.

Most all supplies are in the apartment to put it back together but it's still a mess.1 unit has a roof leak that was improperly fixed (still leaks) and hasn't been messed with since.Tax are 3000 annuallyInsurance around 1200 or lessHis asking price is 165,000 would seller finance with 10% down.I offered 140,000 with him carry the note with 20k down on a 2yr balloon at 5% interest.His "Realtor" said he spike with the guy and he wouldn't do any less then 165k.

I have Excellent credit and ample funds in case of repairs etc.Also the home is in a very good area (close to schools about 1500 sq ft 3 bed 2 bath) Also my brother and father are contractors so that always helps for future maintenance.I thought without paying any realty/ closing fee's this could be a great and profitable way to get my first single family rental going.Any advice/ guidance would be appreciated!

For example, in four 4-unit buildings this is what the rents look like. 585, 610, 615, 585, 585, 615, 630, 585585, 615, 630, 585, 585, 615, 630, 585I'm guessing that some of this variation is due to supply and demand (winter and summer) but are there any other logical reasons as to why this would vary $45 between the high and the low?