Where the property values are way too high to invest in.

I probably would quality for being a trade or business with the amount of hours I put in remodeling and such but since I don't have logs for the past 4 years (since I've had my rentals for much longer), it would be at least 3 to 4 more years before I'd qualify for that.

Try looking at it a slightly different way with some quick math:$900,000 sales price$22,500 cost of purchase (appraisal, points, lender fees, title fees, etc - 2.5%)$90,000 cost of sale (10% commissions, closing costs, buyer credits)$64,000 carrying costs (6 months at 10%)$25,000 additional carrying costs (6 months taxes, utilities, HOA, misc)$100,000 rehab cost (the number used above)$68,500 profit = $530,000 max allowable offer.Some numbers may be a bit high, others may be a bit low. 

There is a high demand for rentals and not nearly enough inventory.

If you have over-improved the unit for the market, it is highly unlikely that you will reap a higher rent price...the market just doesn't support it. 

@Tracy Scott it's highly dependent on the deal, the type of property and the location.In addition to the items others have mentioned, here are some of the biggest potential start-up expenses that I study closely before buying a property:Foundation/structure--this is one of my few "deal breakers", I typically will not purchase a property with significant foundation or structural issues.

@Bryson WilliamsTypically you would have your tenants pay their own utilities since you wouldn't want to cover someone's high water or electricity/gas bills but some cities will put a lien on your property if certain utilities aren't paid.

@Matthew Brown There's some quality lessons learned here and acknowledgement of that is important.

I live in California and like many California Investors prices are just too high in the area I live.

I was able to set and get the rent high enough at the AZ home to cover both the orginal mortgage and the equity loan.