What books are out there with real, accurate real estate information?

@MarcYour food analogy is not entirely accurate.

I gather the info and put into a spreadsheet (neighborhood, bed, bath, list price, list date, year built, zip code, and if its bank owned / short sale, etc).I have a column that has the formula =Today() and then the Days on Market column will subtract todays date from list date, giving me the accurate days on market (matches the mls!).

If your rents are accurate, looks like a solid deal.

The test really wasn't stressful at all, Onlineed was fairly accurate when they said "this is never tested on" or "this is heavily tested."  

You must be able to estimate repairs accurately and also market value once fixed.

You need to do some research and find out what kind of reputation they have, talk to some of their clients and see if they are truly happy, take the properties they are showing you to a third party to verify if the comps are appropriate/accurate, and vet the property manager as well.A good place to begin would be to start a new thread in the forums asking for feedback from anyone who has used them.

Either one or them or perhaps a clerk will know who the research pro's are and point them out.As for getting a cheap, accurate, reliable data source provider, you might luck out.

Don't assume that a real estate agent's idea of market rent is accurate (not sure if that's where you got your figure or not, a lot of new landlords seem to do that at first.)

Make sure the contact a local bank and see what kind of financing you can get so you can run your calcs with accurate numbers.Also, join you local apartment association if you plan to do residential multis.Most books are a waste of time.