For example the lowest ranking members in the markets I operate in receive $840 (before taxes) as single service members and $1,041 (before taxes) when they have dependents, so generally my rents will range from $750-$950 monthly.

I know it can vary by market but are there any general guidelines, rules of thumb that people are using?

https://members.digonline.org/events/Details/dig-general-meeting-creating-a-multi-million-dollar-rental-portfolio-67422?

Generally I go though wholesalers who I have met in person or heard though word of mouth.

Stay away from condos in general unless there is something special about your strategy or the type of condos you buy. 

I think you're ready to purchase a tax-deed the major down-fall is that too many foreign investors and small capital groups come in and buy the best properties near or above market value....There's a bunch of posts on tax-deeds its just you have to spend sometime  learning how to title examine (this is a key skill you will have to learn).1/2) These properties are being "foreclosed" by the local government - in general its state specific for instance in FL it is true they can be redeemed until the second before sale however after you're pretty much done for (however if its a valuable property and any of the previous owners in the chain of title have a bit of cash to throw around you'll be forced to defend yourself in court which can be pretty expensive).

There are some other ways to massage these figures to make it work but this is just a general figure.

But, generally, are sales taxes required by wholesalers?

You should have a documented list of what you charge for typical expenses such as general cleaning should you ever get challenged on withheld fees.Ensure the one that is moving out of a room clean that room to your satisfaction.Did the one that left break her lease?

While they could answer generalities about the neighborhood it would be irresponsible of the Property Manager to give you specifics of that property.