I went to some of the local places that rehabbers use, but really didn't like the colors (yucky orange "stain") nor the quality.  

I too think that sounds a little strange having paint cost more than stain, unless they are glazed with a 2nd color maybe.  

not every house can be done with paint sprayers, it depends where the house is located sprays goes everywhere when near a street can sprays cars, too close to other houses can spray the windows,  depending on the color you will be in big trouble and you will be using lots of more paint do inferior quality 

Some advice:Don't change colors.

If there are already tenants then that probably means they are fine with the current color of the carpet.

The wall paint always needs 2 coats, no matter what I paint over (mostly painting over lighter colors).

I had a pitch book.. people are visual.. my dad taught me the pitch in the early 70s  with all my color coded maps and pictures etc. you lead them through the presentation.. so you present qualify then CLOSE... most can't close don't know how to close and simply can't ask for the order.. that is the key. 

I usually go with a little darker color.

With a hard money lender you get a partner who does not care about the paint color, the rugs, if you redo the roof and the other decisions.

Carpets can be rinsed with a solution of one of these products mixed with the rinse water in the carpet cleaner (test for color fastness first!)