Prof. there are many great paint options.
First down your way is a company named
Resene. They are pretty unique in the fact they post the RGB and L*ab values so you can see right then and there what the color balance looks like.
What you want as far as a color is one of two things. You either want it to be as neutral as possible, that way the projector controls the image and the screen reflects the image and colors the projector is producing as accurately as possible. People are surprised at how accurate colors can be with a neutral gray. The other option is a
'V' curve. That is seen in the RGB values. I have a thread going on neutrals, and the EasyFlex colors are very very nice "V' curves and some are very neutral as well. So here is an example of a nice RGB 'V'-- EasyFlex-04 comes in at 218 212 220. If you were to plot that on an XY graph you would see the 'V' I am talking about. (You can see a plot of what this looks like from the 'V' curve link above).
What you want to see is the Red and Blue components equal or close to each other. The above value is fine. The Green component should be down 5-6 points depending on the shade. The darker the color, the shallower the V needs to be, in other words the line starts becoming flatter. The flatter the line, the more neutral the color is. Darker colors tend to shift colors harder and that is why they have a flatter V and head towards neutral.
Now that the little RGB primer is out of the way, you can go to the Resene website and those RGB numbers should mean something too you now if they didn't before. The EasyFlex gray I mentioned above that Tiddler created is in the Munsell N9 shade range. Most people are fine with this shade, for those that have a lot of ambient lighting problems an N8 shade will help out even more.
The image above is the Munsell gray scale with 0 being black and 10 being white. We are interested in colors basically from N8 up. An N8 gray is in the range of 202 202 202 and a good 'V' color value would be 202 198 202 or close to that. So look on Resene's site and for RGB values and colors that were mentioned.
If you can't locate Resene close to you, what brands of paint do you have available? I was able to find a couple neutral/nice balanced OTS (Off The Shelf) paints for someone in Sweden, so maybe there is something down your way... we just need to know what brands you have available.